// Map implementation -*- C++ -*-
	
	// Copyright (C) 2001-2019 Free Software Foundation, Inc.
	//
	// This file is part of the GNU ISO C++ Library.  This library is free
	// software; you can redistribute it and/or modify it under the
	// terms of the GNU General Public License as published by the
	// Free Software Foundation; either version 3, or (at your option)
	// any later version.
	
	// This library is distributed in the hope that it will be useful,
	// but WITHOUT ANY WARRANTY; without even the implied warranty of
	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	// GNU General Public License for more details.
	
	// Under Section 7 of GPL version 3, you are granted additional
	// permissions described in the GCC Runtime Library Exception, version
	// 3.1, as published by the Free Software Foundation.
	
	// You should have received a copy of the GNU General Public License and
	// a copy of the GCC Runtime Library Exception along with this program;
	// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
	// <http://www.gnu.org/licenses/>.
	
	/*
	 *
	 * Copyright (c) 1994
	 * Hewlett-Packard Company
	 *
	 * Permission to use, copy, modify, distribute and sell this software
	 * and its documentation for any purpose is hereby granted without fee,
	 * provided that the above copyright notice appear in all copies and
	 * that both that copyright notice and this permission notice appear
	 * in supporting documentation.  Hewlett-Packard Company makes no
	 * representations about the suitability of this software for any
	 * purpose.  It is provided "as is" without express or implied warranty.
	 *
	 *
	 * Copyright (c) 1996,1997
	 * Silicon Graphics Computer Systems, Inc.
	 *
	 * Permission to use, copy, modify, distribute and sell this software
	 * and its documentation for any purpose is hereby granted without fee,
	 * provided that the above copyright notice appear in all copies and
	 * that both that copyright notice and this permission notice appear
	 * in supporting documentation.  Silicon Graphics makes no
	 * representations about the suitability of this software for any
	 * purpose.  It is provided "as is" without express or implied warranty.
	 */
	
	/** @file bits/stl_map.h
	 *  This is an internal header file, included by other library headers.
	 *  Do not attempt to use it directly. @headername{map}
	 */
	
	#ifndef _STL_MAP_H
	#define _STL_MAP_H 1
	
	#include <bits/functexcept.h>
	#include <bits/concept_check.h>
	#if __cplusplus >= 201103L
	#include <initializer_list>
	#include <tuple>
	#endif
	
	namespace std _GLIBCXX_VISIBILITY(default)
	{
	_GLIBCXX_BEGIN_NAMESPACE_VERSION
	_GLIBCXX_BEGIN_NAMESPACE_CONTAINER
	
	  template <typename _Key, typename _Tp, typename _Compare, typename _Alloc>
	    class multimap;
	
	  /**
	   *  @brief A standard container made up of (key,value) pairs, which can be
	   *  retrieved based on a key, in logarithmic time.
	   *
	   *  @ingroup associative_containers
	   *
	   *  @tparam _Key  Type of key objects.
	   *  @tparam  _Tp  Type of mapped objects.
	   *  @tparam _Compare  Comparison function object type, defaults to less<_Key>.
	   *  @tparam _Alloc  Allocator type, defaults to
	   *                  allocator<pair<const _Key, _Tp>.
	   *
	   *  Meets the requirements of a <a href="tables.html#65">container</a>, a
	   *  <a href="tables.html#66">reversible container</a>, and an
	   *  <a href="tables.html#69">associative container</a> (using unique keys).
	   *  For a @c map<Key,T> the key_type is Key, the mapped_type is T, and the
	   *  value_type is std::pair<const Key,T>.
	   *
	   *  Maps support bidirectional iterators.
	   *
	   *  The private tree data is declared exactly the same way for map and
	   *  multimap; the distinction is made entirely in how the tree functions are
	   *  called (*_unique versus *_equal, same as the standard).
	  */
	  template <typename _Key, typename _Tp, typename _Compare = std::less<_Key>,
		    typename _Alloc = std::allocator<std::pair<const _Key, _Tp> > >
	    class map
	    {
	    public:
	      typedef _Key					key_type;
	      typedef _Tp					mapped_type;
	      typedef std::pair<const _Key, _Tp>		value_type;
	      typedef _Compare					key_compare;
	      typedef _Alloc					allocator_type;
	
	    private:
	#ifdef _GLIBCXX_CONCEPT_CHECKS
	      // concept requirements
	      typedef typename _Alloc::value_type		_Alloc_value_type;
	# if __cplusplus < 201103L
	      __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
	# endif
	      __glibcxx_class_requires4(_Compare, bool, _Key, _Key,
					_BinaryFunctionConcept)
	      __glibcxx_class_requires2(value_type, _Alloc_value_type, _SameTypeConcept)
	#endif
	
	#if __cplusplus >= 201103L && defined(__STRICT_ANSI__)
	      static_assert(is_same<typename _Alloc::value_type, value_type>::value,
		  "std::map must have the same value_type as its allocator");
	#endif
	
	    public:
	      class value_compare
	      : public std::binary_function<value_type, value_type, bool>
	      {
		friend class map<_Key, _Tp, _Compare, _Alloc>;
	      protected:
		_Compare comp;
	
		value_compare(_Compare __c)
		: comp(__c) { }
	
	      public:
		bool operator()(const value_type& __x, const value_type& __y) const
		{ return comp(__x.first, __y.first); }
	      };
	
	    private:
	      /// This turns a red-black tree into a [multi]map.
	      typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
		rebind<value_type>::other _Pair_alloc_type;
	
	      typedef _Rb_tree<key_type, value_type, _Select1st<value_type>,
			       key_compare, _Pair_alloc_type> _Rep_type;
	
	      /// The actual tree structure.
	      _Rep_type _M_t;
	
	      typedef __gnu_cxx::__alloc_traits<_Pair_alloc_type> _Alloc_traits;
	
	    public:
	      // many of these are specified differently in ISO, but the following are
	      // "functionally equivalent"
	      typedef typename _Alloc_traits::pointer		 pointer;
	      typedef typename _Alloc_traits::const_pointer	 const_pointer;
	      typedef typename _Alloc_traits::reference		 reference;
	      typedef typename _Alloc_traits::const_reference	 const_reference;
	      typedef typename _Rep_type::iterator		 iterator;
	      typedef typename _Rep_type::const_iterator	 const_iterator;
	      typedef typename _Rep_type::size_type		 size_type;
	      typedef typename _Rep_type::difference_type	 difference_type;
	      typedef typename _Rep_type::reverse_iterator	 reverse_iterator;
	      typedef typename _Rep_type::const_reverse_iterator const_reverse_iterator;
	
	#if __cplusplus > 201402L
	      using node_type = typename _Rep_type::node_type;
	      using insert_return_type = typename _Rep_type::insert_return_type;
	#endif
	
	      // [23.3.1.1] construct/copy/destroy
	      // (get_allocator() is also listed in this section)
	
	      /**
	       *  @brief  Default constructor creates no elements.
	       */
	#if __cplusplus < 201103L
	      map() : _M_t() { }
	#else
	      map() = default;
	#endif
	
	      /**
	       *  @brief  Creates a %map with no elements.
	       *  @param  __comp  A comparison object.
	       *  @param  __a  An allocator object.
	       */
	      explicit
	      map(const _Compare& __comp,
		  const allocator_type& __a = allocator_type())
	      : _M_t(__comp, _Pair_alloc_type(__a)) { }
	
	      /**
	       *  @brief  %Map copy constructor.
	       *
	       *  Whether the allocator is copied depends on the allocator traits.
	       */
	#if __cplusplus < 201103L
	      map(const map& __x)
	      : _M_t(__x._M_t) { }
	#else
	      map(const map&) = default;
	
	      /**
	       *  @brief  %Map move constructor.
	       *
	       *  The newly-created %map contains the exact contents of the moved
	       *  instance. The moved instance is a valid, but unspecified, %map.
	       */
	      map(map&&) = default;
	
	      /**
	       *  @brief  Builds a %map from an initializer_list.
	       *  @param  __l  An initializer_list.
	       *  @param  __comp  A comparison object.
	       *  @param  __a  An allocator object.
	       *
	       *  Create a %map consisting of copies of the elements in the
	       *  initializer_list @a __l.
	       *  This is linear in N if the range is already sorted, and NlogN
	       *  otherwise (where N is @a __l.size()).
	       */
	      map(initializer_list<value_type> __l,
		  const _Compare& __comp = _Compare(),
		  const allocator_type& __a = allocator_type())
	      : _M_t(__comp, _Pair_alloc_type(__a))
	      { _M_t._M_insert_range_unique(__l.begin(), __l.end()); }
	
	      /// Allocator-extended default constructor.
	      explicit
	      map(const allocator_type& __a)
	      : _M_t(_Pair_alloc_type(__a)) { }
	
	      /// Allocator-extended copy constructor.
	      map(const map& __m, const allocator_type& __a)
	      : _M_t(__m._M_t, _Pair_alloc_type(__a)) { }
	
	      /// Allocator-extended move constructor.
	      map(map&& __m, const allocator_type& __a)
	      noexcept(is_nothrow_copy_constructible<_Compare>::value
		       && _Alloc_traits::_S_always_equal())
	      : _M_t(std::move(__m._M_t), _Pair_alloc_type(__a)) { }
	
	      /// Allocator-extended initialier-list constructor.
	      map(initializer_list<value_type> __l, const allocator_type& __a)
	      : _M_t(_Pair_alloc_type(__a))
	      { _M_t._M_insert_range_unique(__l.begin(), __l.end()); }
	
	      /// Allocator-extended range constructor.
	      template<typename _InputIterator>
		map(_InputIterator __first, _InputIterator __last,
		    const allocator_type& __a)
		: _M_t(_Pair_alloc_type(__a))
		{ _M_t._M_insert_range_unique(__first, __last); }
	#endif
	
	      /**
	       *  @brief  Builds a %map from a range.
	       *  @param  __first  An input iterator.
	       *  @param  __last  An input iterator.
	       *
	       *  Create a %map consisting of copies of the elements from
	       *  [__first,__last).  This is linear in N if the range is
	       *  already sorted, and NlogN otherwise (where N is
	       *  distance(__first,__last)).
	       */
	      template<typename _InputIterator>
		map(_InputIterator __first, _InputIterator __last)
		: _M_t()
		{ _M_t._M_insert_range_unique(__first, __last); }
	
	      /**
	       *  @brief  Builds a %map from a range.
	       *  @param  __first  An input iterator.
	       *  @param  __last  An input iterator.
	       *  @param  __comp  A comparison functor.
	       *  @param  __a  An allocator object.
	       *
	       *  Create a %map consisting of copies of the elements from
	       *  [__first,__last).  This is linear in N if the range is
	       *  already sorted, and NlogN otherwise (where N is
	       *  distance(__first,__last)).
	       */
	      template<typename _InputIterator>
		map(_InputIterator __first, _InputIterator __last,
		    const _Compare& __comp,
		    const allocator_type& __a = allocator_type())
		: _M_t(__comp, _Pair_alloc_type(__a))
		{ _M_t._M_insert_range_unique(__first, __last); }
	
	#if __cplusplus >= 201103L
	      /**
	       *  The dtor only erases the elements, and note that if the elements
	       *  themselves are pointers, the pointed-to memory is not touched in any
	       *  way.  Managing the pointer is the user's responsibility.
	       */
	      ~map() = default;
	#endif
	
	      /**
	       *  @brief  %Map assignment operator.
	       *
	       *  Whether the allocator is copied depends on the allocator traits.
	       */
	#if __cplusplus < 201103L
	      map&
	      operator=(const map& __x)
	      {
		_M_t = __x._M_t;
		return *this;
	      }
	#else
	      map&
	      operator=(const map&) = default;
	
	      /// Move assignment operator.
	      map&
	      operator=(map&&) = default;
	
	      /**
	       *  @brief  %Map list assignment operator.
	       *  @param  __l  An initializer_list.
	       *
	       *  This function fills a %map with copies of the elements in the
	       *  initializer list @a __l.
	       *
	       *  Note that the assignment completely changes the %map and
	       *  that the resulting %map's size is the same as the number
	       *  of elements assigned.
	       */
	      map&
	      operator=(initializer_list<value_type> __l)
	      {
		_M_t._M_assign_unique(__l.begin(), __l.end());
		return *this;
	      }
	#endif
	
	      /// Get a copy of the memory allocation object.
	      allocator_type
	      get_allocator() const _GLIBCXX_NOEXCEPT
	      { return allocator_type(_M_t.get_allocator()); }
	
	      // iterators
	      /**
	       *  Returns a read/write iterator that points to the first pair in the
	       *  %map.
	       *  Iteration is done in ascending order according to the keys.
	       */
	      iterator
	      begin() _GLIBCXX_NOEXCEPT
	      { return _M_t.begin(); }
	
	      /**
	       *  Returns a read-only (constant) iterator that points to the first pair
	       *  in the %map.  Iteration is done in ascending order according to the
	       *  keys.
	       */
	      const_iterator
	      begin() const _GLIBCXX_NOEXCEPT
	      { return _M_t.begin(); }
	
	      /**
	       *  Returns a read/write iterator that points one past the last
	       *  pair in the %map.  Iteration is done in ascending order
	       *  according to the keys.
	       */
	      iterator
	      end() _GLIBCXX_NOEXCEPT
	      { return _M_t.end(); }
	
	      /**
	       *  Returns a read-only (constant) iterator that points one past the last
	       *  pair in the %map.  Iteration is done in ascending order according to
	       *  the keys.
	       */
	      const_iterator
	      end() const _GLIBCXX_NOEXCEPT
	      { return _M_t.end(); }
	
	      /**
	       *  Returns a read/write reverse iterator that points to the last pair in
	       *  the %map.  Iteration is done in descending order according to the
	       *  keys.
	       */
	      reverse_iterator
	      rbegin() _GLIBCXX_NOEXCEPT
	      { return _M_t.rbegin(); }
	
	      /**
	       *  Returns a read-only (constant) reverse iterator that points to the
	       *  last pair in the %map.  Iteration is done in descending order
	       *  according to the keys.
	       */
	      const_reverse_iterator
	      rbegin() const _GLIBCXX_NOEXCEPT
	      { return _M_t.rbegin(); }
	
	      /**
	       *  Returns a read/write reverse iterator that points to one before the
	       *  first pair in the %map.  Iteration is done in descending order
	       *  according to the keys.
	       */
	      reverse_iterator
	      rend() _GLIBCXX_NOEXCEPT
	      { return _M_t.rend(); }
	
	      /**
	       *  Returns a read-only (constant) reverse iterator that points to one
	       *  before the first pair in the %map.  Iteration is done in descending
	       *  order according to the keys.
	       */
	      const_reverse_iterator
	      rend() const _GLIBCXX_NOEXCEPT
	      { return _M_t.rend(); }
	
	#if __cplusplus >= 201103L
	      /**
	       *  Returns a read-only (constant) iterator that points to the first pair
	       *  in the %map.  Iteration is done in ascending order according to the
	       *  keys.
	       */
	      const_iterator
	      cbegin() const noexcept
	      { return _M_t.begin(); }
	
	      /**
	       *  Returns a read-only (constant) iterator that points one past the last
	       *  pair in the %map.  Iteration is done in ascending order according to
	       *  the keys.
	       */
	      const_iterator
	      cend() const noexcept
	      { return _M_t.end(); }
	
	      /**
	       *  Returns a read-only (constant) reverse iterator that points to the
	       *  last pair in the %map.  Iteration is done in descending order
	       *  according to the keys.
	       */
	      const_reverse_iterator
	      crbegin() const noexcept
	      { return _M_t.rbegin(); }
	
	      /**
	       *  Returns a read-only (constant) reverse iterator that points to one
	       *  before the first pair in the %map.  Iteration is done in descending
	       *  order according to the keys.
	       */
	      const_reverse_iterator
	      crend() const noexcept
	      { return _M_t.rend(); }
	#endif
	
	      // capacity
	      /** Returns true if the %map is empty.  (Thus begin() would equal
	       *  end().)
	      */
	      _GLIBCXX_NODISCARD bool
	      empty() const _GLIBCXX_NOEXCEPT
	      { return _M_t.empty(); }
	
	      /** Returns the size of the %map.  */
	      size_type
	      size() const _GLIBCXX_NOEXCEPT
	      { return _M_t.size(); }
	
	      /** Returns the maximum size of the %map.  */
	      size_type
	      max_size() const _GLIBCXX_NOEXCEPT
	      { return _M_t.max_size(); }
	
	      // [23.3.1.2] element access
	      /**
	       *  @brief  Subscript ( @c [] ) access to %map data.
	       *  @param  __k  The key for which data should be retrieved.
	       *  @return  A reference to the data of the (key,data) %pair.
	       *
	       *  Allows for easy lookup with the subscript ( @c [] )
	       *  operator.  Returns data associated with the key specified in
	       *  subscript.  If the key does not exist, a pair with that key
	       *  is created using default values, which is then returned.
	       *
	       *  Lookup requires logarithmic time.
	       */
	      mapped_type&
	      operator[](const key_type& __k)
	      {
		// concept requirements
		__glibcxx_function_requires(_DefaultConstructibleConcept<mapped_type>)
	
		iterator __i = lower_bound(__k);
		// __i->first is greater than or equivalent to __k.
		if (__i == end() || key_comp()(__k, (*__i).first))
	#if __cplusplus >= 201103L
		  __i = _M_t._M_emplace_hint_unique(__i, std::piecewise_construct,
						    std::tuple<const key_type&>(__k),
						    std::tuple<>());
	#else
		  __i = insert(__i, value_type(__k, mapped_type()));
	#endif
		return (*__i).second;
	      }
	
	#if __cplusplus >= 201103L
	      mapped_type&
	      operator[](key_type&& __k)
	      {
		// concept requirements
		__glibcxx_function_requires(_DefaultConstructibleConcept<mapped_type>)
	
		iterator __i = lower_bound(__k);
		// __i->first is greater than or equivalent to __k.
		if (__i == end() || key_comp()(__k, (*__i).first))
		  __i = _M_t._M_emplace_hint_unique(__i, std::piecewise_construct,
						std::forward_as_tuple(std::move(__k)),
						std::tuple<>());
		return (*__i).second;
	      }
	#endif
	
	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
	      // DR 464. Suggestion for new member functions in standard containers.
	      /**
	       *  @brief  Access to %map data.
	       *  @param  __k  The key for which data should be retrieved.
	       *  @return  A reference to the data whose key is equivalent to @a __k, if
	       *           such a data is present in the %map.
	       *  @throw  std::out_of_range  If no such data is present.
	       */
	      mapped_type&
	      at(const key_type& __k)
	      {
		iterator __i = lower_bound(__k);
		if (__i == end() || key_comp()(__k, (*__i).first))
		  __throw_out_of_range(__N("map::at"));
		return (*__i).second;
	      }
	
	      const mapped_type&
	      at(const key_type& __k) const
	      {
		const_iterator __i = lower_bound(__k);
		if (__i == end() || key_comp()(__k, (*__i).first))
		  __throw_out_of_range(__N("map::at"));
		return (*__i).second;
	      }
	
	      // modifiers
	#if __cplusplus >= 201103L
	      /**
	       *  @brief Attempts to build and insert a std::pair into the %map.
	       *
	       *  @param __args  Arguments used to generate a new pair instance (see
	       *	        std::piecewise_contruct for passing arguments to each
	       *	        part of the pair constructor).
	       *
	       *  @return  A pair, of which the first element is an iterator that points
	       *           to the possibly inserted pair, and the second is a bool that
	       *           is true if the pair was actually inserted.
	       *
	       *  This function attempts to build and insert a (key, value) %pair into
	       *  the %map.
	       *  A %map relies on unique keys and thus a %pair is only inserted if its
	       *  first element (the key) is not already present in the %map.
	       *
	       *  Insertion requires logarithmic time.
	       */
	      template<typename... _Args>
		std::pair<iterator, bool>
		emplace(_Args&&... __args)
		{ return _M_t._M_emplace_unique(std::forward<_Args>(__args)...); }
	
	      /**
	       *  @brief Attempts to build and insert a std::pair into the %map.
	       *
	       *  @param  __pos  An iterator that serves as a hint as to where the pair
	       *                should be inserted.
	       *  @param  __args  Arguments used to generate a new pair instance (see
	       *	         std::piecewise_contruct for passing arguments to each
	       *	         part of the pair constructor).
	       *  @return An iterator that points to the element with key of the
	       *          std::pair built from @a __args (may or may not be that
	       *          std::pair).
	       *
	       *  This function is not concerned about whether the insertion took place,
	       *  and thus does not return a boolean like the single-argument emplace()
	       *  does.
	       *  Note that the first parameter is only a hint and can potentially
	       *  improve the performance of the insertion process. A bad hint would
	       *  cause no gains in efficiency.
	       *
	       *  See
	       *  https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
	       *  for more on @a hinting.
	       *
	       *  Insertion requires logarithmic time (if the hint is not taken).
	       */
	      template<typename... _Args>
		iterator
		emplace_hint(const_iterator __pos, _Args&&... __args)
		{
		  return _M_t._M_emplace_hint_unique(__pos,

						     std::forward<_Args>(__args)...);
		}
	#endif
	
	#if __cplusplus > 201402L
	      /// Extract a node.
	      node_type
	      extract(const_iterator __pos)
	      {
		__glibcxx_assert(__pos != end());
		return _M_t.extract(__pos);
	      }
	
	      /// Extract a node.
	      node_type
	      extract(const key_type& __x)
	      { return _M_t.extract(__x); }
	
	      /// Re-insert an extracted node.
	      insert_return_type
	      insert(node_type&& __nh)
	      { return _M_t._M_reinsert_node_unique(std::move(__nh)); }
	
	      /// Re-insert an extracted node.
	      iterator
	      insert(const_iterator __hint, node_type&& __nh)
	      { return _M_t._M_reinsert_node_hint_unique(__hint, std::move(__nh)); }
	
	      template<typename, typename>
		friend class std::_Rb_tree_merge_helper;
	
	      template<typename _C2>
		void
		merge(map<_Key, _Tp, _C2, _Alloc>& __source)
		{
		  using _Merge_helper = _Rb_tree_merge_helper<map, _C2>;
		  _M_t._M_merge_unique(_Merge_helper::_S_get_tree(__source));
		}
	
	      template<typename _C2>
		void
		merge(map<_Key, _Tp, _C2, _Alloc>&& __source)
		{ merge(__source); }
	
	      template<typename _C2>
		void
		merge(multimap<_Key, _Tp, _C2, _Alloc>& __source)
		{
		  using _Merge_helper = _Rb_tree_merge_helper<map, _C2>;
		  _M_t._M_merge_unique(_Merge_helper::_S_get_tree(__source));
		}
	
	      template<typename _C2>
		void
		merge(multimap<_Key, _Tp, _C2, _Alloc>&& __source)
		{ merge(__source); }
	#endif // C++17
	
	#if __cplusplus > 201402L
	#define __cpp_lib_map_try_emplace 201411
	      /**
	       *  @brief Attempts to build and insert a std::pair into the %map.
	       *
	       *  @param __k    Key to use for finding a possibly existing pair in
	       *                the map.
	       *  @param __args  Arguments used to generate the .second for a new pair
	       *                instance.
	       *
	       *  @return  A pair, of which the first element is an iterator that points
	       *           to the possibly inserted pair, and the second is a bool that
	       *           is true if the pair was actually inserted.
	       *
	       *  This function attempts to build and insert a (key, value) %pair into
	       *  the %map.
	       *  A %map relies on unique keys and thus a %pair is only inserted if its
	       *  first element (the key) is not already present in the %map.
	       *  If a %pair is not inserted, this function has no effect.
	       *
	       *  Insertion requires logarithmic time.
	       */
	      template <typename... _Args>
		pair<iterator, bool>
		try_emplace(const key_type& __k, _Args&&... __args)
		{
		  iterator __i = lower_bound(__k);
		  if (__i == end() || key_comp()(__k, (*__i).first))
		    {
		      __i = emplace_hint(__i, std::piecewise_construct,
					 std::forward_as_tuple(__k),
					 std::forward_as_tuple(
					   std::forward<_Args>(__args)...));
		      return {__i, true};
		    }
		  return {__i, false};
		}
	
	      // move-capable overload
	      template <typename... _Args>
		pair<iterator, bool>
		try_emplace(key_type&& __k, _Args&&... __args)
		{
		  iterator __i = lower_bound(__k);
		  if (__i == end() || key_comp()(__k, (*__i).first))
		    {
		      __i = emplace_hint(__i, std::piecewise_construct,
					 std::forward_as_tuple(std::move(__k)),
					 std::forward_as_tuple(
					   std::forward<_Args>(__args)...));
		      return {__i, true};
		    }
		  return {__i, false};
		}
	
	      /**
	       *  @brief Attempts to build and insert a std::pair into the %map.
	       *
	       *  @param  __hint  An iterator that serves as a hint as to where the
	       *                  pair should be inserted.
	       *  @param __k    Key to use for finding a possibly existing pair in
	       *                the map.
	       *  @param __args  Arguments used to generate the .second for a new pair
	       *                instance.
	       *  @return An iterator that points to the element with key of the
	       *          std::pair built from @a __args (may or may not be that
	       *          std::pair).
	       *
	       *  This function is not concerned about whether the insertion took place,
	       *  and thus does not return a boolean like the single-argument
	       *  try_emplace() does. However, if insertion did not take place,
	       *  this function has no effect.
	       *  Note that the first parameter is only a hint and can potentially
	       *  improve the performance of the insertion process. A bad hint would
	       *  cause no gains in efficiency.
	       *
	       *  See
	       *  https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
	       *  for more on @a hinting.
	       *
	       *  Insertion requires logarithmic time (if the hint is not taken).
	       */
	      template <typename... _Args>
		iterator
		try_emplace(const_iterator __hint, const key_type& __k,
			    _Args&&... __args)
		{
		  iterator __i;
		  auto __true_hint = _M_t._M_get_insert_hint_unique_pos(__hint, __k);
		  if (__true_hint.second)
		    __i = emplace_hint(iterator(__true_hint.second),
				       std::piecewise_construct,
				       std::forward_as_tuple(__k),
				       std::forward_as_tuple(
					 std::forward<_Args>(__args)...));
		  else
		    __i = iterator(__true_hint.first);
		  return __i;
		}
	
	      // move-capable overload
	      template <typename... _Args>
		iterator
		try_emplace(const_iterator __hint, key_type&& __k, _Args&&... __args)
		{
		  iterator __i;
		  auto __true_hint = _M_t._M_get_insert_hint_unique_pos(__hint, __k);
		  if (__true_hint.second)
		    __i = emplace_hint(iterator(__true_hint.second),
				       std::piecewise_construct,
				       std::forward_as_tuple(std::move(__k)),
				       std::forward_as_tuple(
					 std::forward<_Args>(__args)...));
		  else
		    __i = iterator(__true_hint.first);
		  return __i;
		}
	#endif
	
	      /**
	       *  @brief Attempts to insert a std::pair into the %map.
	       *  @param __x Pair to be inserted (see std::make_pair for easy
	       *	     creation of pairs).
	       *
	       *  @return  A pair, of which the first element is an iterator that
	       *           points to the possibly inserted pair, and the second is
	       *           a bool that is true if the pair was actually inserted.
	       *
	       *  This function attempts to insert a (key, value) %pair into the %map.
	       *  A %map relies on unique keys and thus a %pair is only inserted if its
	       *  first element (the key) is not already present in the %map.
	       *
	       *  Insertion requires logarithmic time.
	       *  @{
	       */
	      std::pair<iterator, bool>
	      insert(const value_type& __x)
	      { return _M_t._M_insert_unique(__x); }
	
	#if __cplusplus >= 201103L
	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
	      // 2354. Unnecessary copying when inserting into maps with braced-init
	      std::pair<iterator, bool>
	      insert(value_type&& __x)
	      { return _M_t._M_insert_unique(std::move(__x)); }
	
	      template<typename _Pair>
		__enable_if_t<is_constructible<value_type, _Pair>::value,
			      pair<iterator, bool>>
		insert(_Pair&& __x)
		{ return _M_t._M_emplace_unique(std::forward<_Pair>(__x)); }
	#endif
	      // @}
	
	#if __cplusplus >= 201103L
	      /**
	       *  @brief Attempts to insert a list of std::pairs into the %map.
	       *  @param  __list  A std::initializer_list<value_type> of pairs to be
	       *                  inserted.
	       *
	       *  Complexity similar to that of the range constructor.
	       */
	      void
	      insert(std::initializer_list<value_type> __list)
	      { insert(__list.begin(), __list.end()); }
	#endif
	
	      /**
	       *  @brief Attempts to insert a std::pair into the %map.
	       *  @param  __position  An iterator that serves as a hint as to where the
	       *                    pair should be inserted.
	       *  @param  __x  Pair to be inserted (see std::make_pair for easy creation
	       *               of pairs).
	       *  @return An iterator that points to the element with key of
	       *           @a __x (may or may not be the %pair passed in).
	       *
	
	       *  This function is not concerned about whether the insertion
	       *  took place, and thus does not return a boolean like the
	       *  single-argument insert() does.  Note that the first
	       *  parameter is only a hint and can potentially improve the
	       *  performance of the insertion process.  A bad hint would
	       *  cause no gains in efficiency.
	       *
	       *  See
	       *  https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
	       *  for more on @a hinting.
	       *
	       *  Insertion requires logarithmic time (if the hint is not taken).
	       *  @{
	       */
	      iterator
	#if __cplusplus >= 201103L
	      insert(const_iterator __position, const value_type& __x)
	#else
	      insert(iterator __position, const value_type& __x)
	#endif
	      { return _M_t._M_insert_unique_(__position, __x); }
	
	#if __cplusplus >= 201103L
	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
	      // 2354. Unnecessary copying when inserting into maps with braced-init
	      iterator
	      insert(const_iterator __position, value_type&& __x)
	      { return _M_t._M_insert_unique_(__position, std::move(__x)); }
	
	      template<typename _Pair>
		__enable_if_t<is_constructible<value_type, _Pair>::value, iterator>
		insert(const_iterator __position, _Pair&& __x)
		{
		  return _M_t._M_emplace_hint_unique(__position,
						     std::forward<_Pair>(__x));
		}
	#endif
	      // @}
	
	      /**
	       *  @brief Template function that attempts to insert a range of elements.
	       *  @param  __first  Iterator pointing to the start of the range to be
	       *                   inserted.
	       *  @param  __last  Iterator pointing to the end of the range.
	       *
	       *  Complexity similar to that of the range constructor.
	       */
	      template<typename _InputIterator>
		void
		insert(_InputIterator __first, _InputIterator __last)
		{ _M_t._M_insert_range_unique(__first, __last); }
	
	#if __cplusplus > 201402L
	#define __cpp_lib_map_insertion 201411
	      /**
	       *  @brief Attempts to insert or assign a std::pair into the %map.
	       *  @param __k    Key to use for finding a possibly existing pair in
	       *                the map.
	       *  @param __obj  Argument used to generate the .second for a pair
	       *                instance.
	       *
	       *  @return  A pair, of which the first element is an iterator that
	       *           points to the possibly inserted pair, and the second is
	       *           a bool that is true if the pair was actually inserted.
	       *
	       *  This function attempts to insert a (key, value) %pair into the %map.
	       *  A %map relies on unique keys and thus a %pair is only inserted if its
	       *  first element (the key) is not already present in the %map.
	       *  If the %pair was already in the %map, the .second of the %pair
	       *  is assigned from __obj.
	       *
	       *  Insertion requires logarithmic time.
	       */
	      template <typename _Obj>
		pair<iterator, bool>
		insert_or_assign(const key_type& __k, _Obj&& __obj)
		{
		  iterator __i = lower_bound(__k);
		  if (__i == end() || key_comp()(__k, (*__i).first))
		    {
		      __i = emplace_hint(__i, std::piecewise_construct,
					 std::forward_as_tuple(__k),
					 std::forward_as_tuple(
					   std::forward<_Obj>(__obj)));
		      return {__i, true};
		    }
		  (*__i).second = std::forward<_Obj>(__obj);
		  return {__i, false};
		}
	
	      // move-capable overload
	      template <typename _Obj>
		pair<iterator, bool>
		insert_or_assign(key_type&& __k, _Obj&& __obj)
		{
		  iterator __i = lower_bound(__k);
		  if (__i == end() || key_comp()(__k, (*__i).first))
		    {
		      __i = emplace_hint(__i, std::piecewise_construct,
					 std::forward_as_tuple(std::move(__k)),
					 std::forward_as_tuple(
					   std::forward<_Obj>(__obj)));
		      return {__i, true};
		    }
		  (*__i).second = std::forward<_Obj>(__obj);
		  return {__i, false};
		}
	
	      /**
	       *  @brief Attempts to insert or assign a std::pair into the %map.
	       *  @param  __hint  An iterator that serves as a hint as to where the
	       *                  pair should be inserted.
	       *  @param __k    Key to use for finding a possibly existing pair in
	       *                the map.
	       *  @param __obj  Argument used to generate the .second for a pair
	       *                instance.
	       *
	       *  @return An iterator that points to the element with key of
	       *           @a __x (may or may not be the %pair passed in).
	       *
	       *  This function attempts to insert a (key, value) %pair into the %map.
	       *  A %map relies on unique keys and thus a %pair is only inserted if its
	       *  first element (the key) is not already present in the %map.
	       *  If the %pair was already in the %map, the .second of the %pair
	       *  is assigned from __obj.
	       *
	       *  Insertion requires logarithmic time.
	       */
	      template <typename _Obj>
		iterator
		insert_or_assign(const_iterator __hint,
				 const key_type& __k, _Obj&& __obj)
		{
		  iterator __i;
		  auto __true_hint = _M_t._M_get_insert_hint_unique_pos(__hint, __k);
		  if (__true_hint.second)
		    {
		      return emplace_hint(iterator(__true_hint.second),
					  std::piecewise_construct,
					  std::forward_as_tuple(__k),
					  std::forward_as_tuple(
					    std::forward<_Obj>(__obj)));
		    }
		  __i = iterator(__true_hint.first);
		  (*__i).second = std::forward<_Obj>(__obj);
		  return __i;
		}
	
	      // move-capable overload
	      template <typename _Obj>
		iterator
		insert_or_assign(const_iterator __hint, key_type&& __k, _Obj&& __obj)
		{
		  iterator __i;
		  auto __true_hint = _M_t._M_get_insert_hint_unique_pos(__hint, __k);
		  if (__true_hint.second)
		    {
		      return emplace_hint(iterator(__true_hint.second),
					  std::piecewise_construct,
					  std::forward_as_tuple(std::move(__k)),
					  std::forward_as_tuple(
					    std::forward<_Obj>(__obj)));
		    }
		  __i = iterator(__true_hint.first);
		  (*__i).second = std::forward<_Obj>(__obj);
		  return __i;
		}
	#endif
	
	#if __cplusplus >= 201103L
	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
	      // DR 130. Associative erase should return an iterator.
	      /**
	       *  @brief Erases an element from a %map.
	       *  @param  __position  An iterator pointing to the element to be erased.
	       *  @return An iterator pointing to the element immediately following
	       *          @a position prior to the element being erased. If no such
	       *          element exists, end() is returned.
	       *
	       *  This function erases an element, pointed to by the given
	       *  iterator, from a %map.  Note that this function only erases
	       *  the element, and that if the element is itself a pointer,
	       *  the pointed-to memory is not touched in any way.  Managing
	       *  the pointer is the user's responsibility.
	       *
	       *  @{
	       */
	      iterator
	      erase(const_iterator __position)
	      { return _M_t.erase(__position); }
	
	      // LWG 2059
	      _GLIBCXX_ABI_TAG_CXX11
	      iterator
	      erase(iterator __position)
	      { return _M_t.erase(__position); }
	      // @}
	#else
	      /**
	       *  @brief Erases an element from a %map.
	       *  @param  __position  An iterator pointing to the element to be erased.
	       *
	       *  This function erases an element, pointed to by the given
	       *  iterator, from a %map.  Note that this function only erases
	       *  the element, and that if the element is itself a pointer,
	       *  the pointed-to memory is not touched in any way.  Managing
	       *  the pointer is the user's responsibility.
	       */
	      void
	      erase(iterator __position)
	      { _M_t.erase(__position); }
	#endif
	
	      /**
	       *  @brief Erases elements according to the provided key.
	       *  @param  __x  Key of element to be erased.
	       *  @return  The number of elements erased.
	       *
	       *  This function erases all the elements located by the given key from
	       *  a %map.
	       *  Note that this function only erases the element, and that if
	       *  the element is itself a pointer, the pointed-to memory is not touched
	       *  in any way.  Managing the pointer is the user's responsibility.
	       */
	      size_type
	      erase(const key_type& __x)
	      { return _M_t.erase(__x); }
	
	#if __cplusplus >= 201103L
	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
	      // DR 130. Associative erase should return an iterator.
	      /**
	       *  @brief Erases a [first,last) range of elements from a %map.
	       *  @param  __first  Iterator pointing to the start of the range to be
	       *                   erased.
	       *  @param __last Iterator pointing to the end of the range to
	       *                be erased.
	       *  @return The iterator @a __last.
	       *
	       *  This function erases a sequence of elements from a %map.
	       *  Note that this function only erases the element, and that if
	       *  the element is itself a pointer, the pointed-to memory is not touched
	       *  in any way.  Managing the pointer is the user's responsibility.
	       */
	      iterator
	      erase(const_iterator __first, const_iterator __last)
	      { return _M_t.erase(__first, __last); }
	#else
	      /**
	       *  @brief Erases a [__first,__last) range of elements from a %map.
	       *  @param  __first  Iterator pointing to the start of the range to be
	       *                   erased.
	       *  @param __last Iterator pointing to the end of the range to
	       *                be erased.
	       *
	       *  This function erases a sequence of elements from a %map.
	       *  Note that this function only erases the element, and that if
	       *  the element is itself a pointer, the pointed-to memory is not touched
	       *  in any way.  Managing the pointer is the user's responsibility.
	       */
	      void
	      erase(iterator __first, iterator __last)
	      { _M_t.erase(__first, __last); }
	#endif
	
	      /**
	       *  @brief  Swaps data with another %map.
	       *  @param  __x  A %map of the same element and allocator types.
	       *
	       *  This exchanges the elements between two maps in constant
	       *  time.  (It is only swapping a pointer, an integer, and an
	       *  instance of the @c Compare type (which itself is often
	       *  stateless and empty), so it should be quite fast.)  Note
	       *  that the global std::swap() function is specialized such
	       *  that std::swap(m1,m2) will feed to this function.
	       *
	       *  Whether the allocators are swapped depends on the allocator traits.
	       */
	      void
	      swap(map& __x)
	      _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Compare>::value)
	      { _M_t.swap(__x._M_t); }
	
	      /**
	       *  Erases all elements in a %map.  Note that this function only
	       *  erases the elements, and that if the elements themselves are
	       *  pointers, the pointed-to memory is not touched in any way.
	       *  Managing the pointer is the user's responsibility.
	       */
	      void
	      clear() _GLIBCXX_NOEXCEPT
	      { _M_t.clear(); }
	
	      // observers
	      /**
	       *  Returns the key comparison object out of which the %map was
	       *  constructed.
	       */
	      key_compare
	      key_comp() const
	      { return _M_t.key_comp(); }
	
	      /**
	       *  Returns a value comparison object, built from the key comparison
	       *  object out of which the %map was constructed.
	       */
	      value_compare
	      value_comp() const
	      { return value_compare(_M_t.key_comp()); }
	
	      // [23.3.1.3] map operations
	
	      //@{
	      /**
	       *  @brief Tries to locate an element in a %map.
	       *  @param  __x  Key of (key, value) %pair to be located.
	       *  @return  Iterator pointing to sought-after element, or end() if not
	       *           found.
	       *
	       *  This function takes a key and tries to locate the element with which
	       *  the key matches.  If successful the function returns an iterator
	       *  pointing to the sought after %pair.  If unsuccessful it returns the
	       *  past-the-end ( @c end() ) iterator.
	       */
	
	      iterator
	      find(const key_type& __x)
	      { return _M_t.find(__x); }
	
	#if __cplusplus > 201103L
	      template<typename _Kt>
		auto
		find(const _Kt& __x) -> decltype(_M_t._M_find_tr(__x))
		{ return _M_t._M_find_tr(__x); }
	#endif
	      //@}
	
	      //@{
	      /**
	       *  @brief Tries to locate an element in a %map.
	       *  @param  __x  Key of (key, value) %pair to be located.
	       *  @return  Read-only (constant) iterator pointing to sought-after
	       *           element, or end() if not found.
	       *
	       *  This function takes a key and tries to locate the element with which
	       *  the key matches.  If successful the function returns a constant
	       *  iterator pointing to the sought after %pair. If unsuccessful it
	       *  returns the past-the-end ( @c end() ) iterator.
	       */
	
	      const_iterator
	      find(const key_type& __x) const
	      { return _M_t.find(__x); }
	
	#if __cplusplus > 201103L
	      template<typename _Kt>
		auto
		find(const _Kt& __x) const -> decltype(_M_t._M_find_tr(__x))
		{ return _M_t._M_find_tr(__x); }
	#endif
	      //@}
	
	      //@{
	      /**
	       *  @brief  Finds the number of elements with given key.
	       *  @param  __x  Key of (key, value) pairs to be located.
	       *  @return  Number of elements with specified key.
	       *
	       *  This function only makes sense for multimaps; for map the result will
	       *  either be 0 (not present) or 1 (present).
	       */
	      size_type
	      count(const key_type& __x) const
	      { return _M_t.find(__x) == _M_t.end() ? 0 : 1; }
	
	#if __cplusplus > 201103L
	      template<typename _Kt>
		auto
		count(const _Kt& __x) const -> decltype(_M_t._M_count_tr(__x))
		{ return _M_t._M_count_tr(__x); }
	#endif
	      //@}
	
	#if __cplusplus > 201703L
	      //@{
	      /**
	       *  @brief  Finds whether an element with the given key exists.
	       *  @param  __x  Key of (key, value) pairs to be located.
	       *  @return  True if there is an element with the specified key.
	       */
	      bool
	      contains(const key_type& __x) const
	      { return _M_t.find(__x) != _M_t.end(); }
	
	      template<typename _Kt>
		auto
		contains(const _Kt& __x) const
		-> decltype(_M_t._M_find_tr(__x), void(), true)
		{ return _M_t._M_find_tr(__x) != _M_t.end(); }
	      //@}
	#endif
	
	      //@{
	      /**
	       *  @brief Finds the beginning of a subsequence matching given key.
	       *  @param  __x  Key of (key, value) pair to be located.
	       *  @return  Iterator pointing to first element equal to or greater
	       *           than key, or end().
	       *
	       *  This function returns the first element of a subsequence of elements
	       *  that matches the given key.  If unsuccessful it returns an iterator
	       *  pointing to the first element that has a greater value than given key
	       *  or end() if no such element exists.
	       */
	      iterator
	      lower_bound(const key_type& __x)
	      { return _M_t.lower_bound(__x); }
	
	#if __cplusplus > 201103L
	      template<typename _Kt>
		auto
		lower_bound(const _Kt& __x)
		-> decltype(iterator(_M_t._M_lower_bound_tr(__x)))
		{ return iterator(_M_t._M_lower_bound_tr(__x)); }
	#endif
	      //@}
	
	      //@{
	      /**
	       *  @brief Finds the beginning of a subsequence matching given key.
	       *  @param  __x  Key of (key, value) pair to be located.
	       *  @return  Read-only (constant) iterator pointing to first element
	       *           equal to or greater than key, or end().
	       *
	       *  This function returns the first element of a subsequence of elements
	       *  that matches the given key.  If unsuccessful it returns an iterator
	       *  pointing to the first element that has a greater value than given key
	       *  or end() if no such element exists.
	       */
	      const_iterator
	      lower_bound(const key_type& __x) const
	      { return _M_t.lower_bound(__x); }
	
	#if __cplusplus > 201103L
	      template<typename _Kt>
		auto
		lower_bound(const _Kt& __x) const
		-> decltype(const_iterator(_M_t._M_lower_bound_tr(__x)))
		{ return const_iterator(_M_t._M_lower_bound_tr(__x)); }
	#endif
	      //@}
	
	      //@{
	      /**
	       *  @brief Finds the end of a subsequence matching given key.
	       *  @param  __x  Key of (key, value) pair to be located.
	       *  @return Iterator pointing to the first element
	       *          greater than key, or end().
	       */
	      iterator
	      upper_bound(const key_type& __x)
	      { return _M_t.upper_bound(__x); }
	
	#if __cplusplus > 201103L
	      template<typename _Kt>
		auto
		upper_bound(const _Kt& __x)
		-> decltype(iterator(_M_t._M_upper_bound_tr(__x)))
		{ return iterator(_M_t._M_upper_bound_tr(__x)); }
	#endif
	      //@}
	
	      //@{
	      /**
	       *  @brief Finds the end of a subsequence matching given key.
	       *  @param  __x  Key of (key, value) pair to be located.
	       *  @return  Read-only (constant) iterator pointing to first iterator
	       *           greater than key, or end().
	       */
	      const_iterator
	      upper_bound(const key_type& __x) const
	      { return _M_t.upper_bound(__x); }
	
	#if __cplusplus > 201103L
	      template<typename _Kt>
		auto
		upper_bound(const _Kt& __x) const
		-> decltype(const_iterator(_M_t._M_upper_bound_tr(__x)))
		{ return const_iterator(_M_t._M_upper_bound_tr(__x)); }
	#endif
	      //@}
	
	      //@{
	      /**
	       *  @brief Finds a subsequence matching given key.
	       *  @param  __x  Key of (key, value) pairs to be located.
	       *  @return  Pair of iterators that possibly points to the subsequence
	       *           matching given key.
	       *
	       *  This function is equivalent to
	       *  @code
	       *    std::make_pair(c.lower_bound(val),
	       *                   c.upper_bound(val))
	       *  @endcode
	       *  (but is faster than making the calls separately).
	       *
	       *  This function probably only makes sense for multimaps.
	       */
	      std::pair<iterator, iterator>
	      equal_range(const key_type& __x)
	      { return _M_t.equal_range(__x); }
	
	#if __cplusplus > 201103L
	      template<typename _Kt>
		auto
		equal_range(const _Kt& __x)
		-> decltype(pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)))
		{ return pair<iterator, iterator>(_M_t._M_equal_range_tr(__x)); }
	#endif
	      //@}
	
	      //@{
	      /**
	       *  @brief Finds a subsequence matching given key.
	       *  @param  __x  Key of (key, value) pairs to be located.
	       *  @return  Pair of read-only (constant) iterators that possibly points
	       *           to the subsequence matching given key.
	       *
	       *  This function is equivalent to
	       *  @code
	       *    std::make_pair(c.lower_bound(val),
	       *                   c.upper_bound(val))
	       *  @endcode
	       *  (but is faster than making the calls separately).
	       *
	       *  This function probably only makes sense for multimaps.
	       */
	      std::pair<const_iterator, const_iterator>
	      equal_range(const key_type& __x) const
	      { return _M_t.equal_range(__x); }
	
	#if __cplusplus > 201103L
	      template<typename _Kt>
		auto
		equal_range(const _Kt& __x) const
		-> decltype(pair<const_iterator, const_iterator>(
		      _M_t._M_equal_range_tr(__x)))
		{
		  return pair<const_iterator, const_iterator>(
		      _M_t._M_equal_range_tr(__x));
		}
	#endif
	      //@}
	
	      template<typename _K1, typename _T1, typename _C1, typename _A1>
		friend bool
		operator==(const map<_K1, _T1, _C1, _A1>&,
			   const map<_K1, _T1, _C1, _A1>&);
	
	      template<typename _K1, typename _T1, typename _C1, typename _A1>
		friend bool
		operator<(const map<_K1, _T1, _C1, _A1>&,
			  const map<_K1, _T1, _C1, _A1>&);
	    };
	
	
	#if __cpp_deduction_guides >= 201606
	
	  template<typename _InputIterator,
		   typename _Compare = less<__iter_key_t<_InputIterator>>,
		   typename _Allocator = allocator<__iter_to_alloc_t<_InputIterator>>,
		   typename = _RequireInputIter<_InputIterator>,
		   typename = _RequireNotAllocator<_Compare>,
		   typename = _RequireAllocator<_Allocator>>
	    map(_InputIterator, _InputIterator,
		_Compare = _Compare(), _Allocator = _Allocator())
	    -> map<__iter_key_t<_InputIterator>, __iter_val_t<_InputIterator>,
		   _Compare, _Allocator>;
	
	  template<typename _Key, typename _Tp, typename _Compare = less<_Key>,
		   typename _Allocator = allocator<pair<const _Key, _Tp>>,
		   typename = _RequireNotAllocator<_Compare>,
		   typename = _RequireAllocator<_Allocator>>
	    map(initializer_list<pair<_Key, _Tp>>,
		_Compare = _Compare(), _Allocator = _Allocator())
	    -> map<_Key, _Tp, _Compare, _Allocator>;
	
	  template <typename _InputIterator, typename _Allocator,
		    typename = _RequireInputIter<_InputIterator>,
		    typename = _RequireAllocator<_Allocator>>
	    map(_InputIterator, _InputIterator, _Allocator)
	    -> map<__iter_key_t<_InputIterator>, __iter_val_t<_InputIterator>,
		   less<__iter_key_t<_InputIterator>>, _Allocator>;
	
	  template<typename _Key, typename _Tp, typename _Allocator,
		   typename = _RequireAllocator<_Allocator>>
	    map(initializer_list<pair<_Key, _Tp>>, _Allocator)
	    -> map<_Key, _Tp, less<_Key>, _Allocator>;
	
	#endif
	
	  /**
	   *  @brief  Map equality comparison.
	   *  @param  __x  A %map.
	   *  @param  __y  A %map of the same type as @a x.
	   *  @return  True iff the size and elements of the maps are equal.
	   *
	   *  This is an equivalence relation.  It is linear in the size of the
	   *  maps.  Maps are considered equivalent if their sizes are equal,
	   *  and if corresponding elements compare equal.
	  */
	  template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
	    inline bool
	    operator==(const map<_Key, _Tp, _Compare, _Alloc>& __x,
		       const map<_Key, _Tp, _Compare, _Alloc>& __y)
	    { return __x._M_t == __y._M_t; }
	
	  /**
	   *  @brief  Map ordering relation.
	   *  @param  __x  A %map.
	   *  @param  __y  A %map of the same type as @a x.
	   *  @return  True iff @a x is lexicographically less than @a y.
	   *
	   *  This is a total ordering relation.  It is linear in the size of the
	   *  maps.  The elements must be comparable with @c <.
	   *
	   *  See std::lexicographical_compare() for how the determination is made.
	  */
	  template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
	    inline bool
	    operator<(const map<_Key, _Tp, _Compare, _Alloc>& __x,
		      const map<_Key, _Tp, _Compare, _Alloc>& __y)
	    { return __x._M_t < __y._M_t; }
	
	  /// Based on operator==
	  template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
	    inline bool
	    operator!=(const map<_Key, _Tp, _Compare, _Alloc>& __x,
		       const map<_Key, _Tp, _Compare, _Alloc>& __y)
	    { return !(__x == __y); }
	
	  /// Based on operator<
	  template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
	    inline bool
	    operator>(const map<_Key, _Tp, _Compare, _Alloc>& __x,
		      const map<_Key, _Tp, _Compare, _Alloc>& __y)
	    { return __y < __x; }
	
	  /// Based on operator<
	  template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
	    inline bool
	    operator<=(const map<_Key, _Tp, _Compare, _Alloc>& __x,
		       const map<_Key, _Tp, _Compare, _Alloc>& __y)
	    { return !(__y < __x); }
	
	  /// Based on operator<
	  template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
	    inline bool
	    operator>=(const map<_Key, _Tp, _Compare, _Alloc>& __x,
		       const map<_Key, _Tp, _Compare, _Alloc>& __y)
	    { return !(__x < __y); }
	
	  /// See std::map::swap().
	  template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
	    inline void
	    swap(map<_Key, _Tp, _Compare, _Alloc>& __x,
		 map<_Key, _Tp, _Compare, _Alloc>& __y)
	    _GLIBCXX_NOEXCEPT_IF(noexcept(__x.swap(__y)))
	    { __x.swap(__y); }
	
	_GLIBCXX_END_NAMESPACE_CONTAINER
	
	#if __cplusplus > 201402L
	  // Allow std::map access to internals of compatible maps.
	  template<typename _Key, typename _Val, typename _Cmp1, typename _Alloc,
		   typename _Cmp2>
	    struct
	    _Rb_tree_merge_helper<_GLIBCXX_STD_C::map<_Key, _Val, _Cmp1, _Alloc>,
				  _Cmp2>
	    {
	    private:
	      friend class _GLIBCXX_STD_C::map<_Key, _Val, _Cmp1, _Alloc>;
	
	      static auto&
	      _S_get_tree(_GLIBCXX_STD_C::map<_Key, _Val, _Cmp2, _Alloc>& __map)
	      { return __map._M_t; }
	
	      static auto&
	      _S_get_tree(_GLIBCXX_STD_C::multimap<_Key, _Val, _Cmp2, _Alloc>& __map)
	      { return __map._M_t; }
	    };
	#endif // C++17
	
	_GLIBCXX_END_NAMESPACE_VERSION
	} // namespace std
	
	#endif /* _STL_MAP_H */