namespace std {
template<class Key, class Compare = less<Key>, class KeyContainer = vector<Key>>
class flat_set {
public:
using key_type = Key;
using value_type = Key;
using key_compare = Compare;
using value_compare = Compare;
using reference = value_type&;
using const_reference = const value_type&;
using size_type = typename KeyContainer::size_type;
using difference_type = typename KeyContainer::difference_type;
using iterator = implementation-defined;
using const_iterator = implementation-defined;
using reverse_iterator = std::reverse_iterator<iterator>;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
using container_type = KeyContainer;
constexpr flat_set() : flat_set(key_compare()) { }
constexpr explicit flat_set(const key_compare& comp)
: c(), compare(comp) { }
constexpr explicit flat_set(container_type cont, const key_compare& comp = key_compare());
constexpr flat_set(sorted_unique_t, container_type cont,
const key_compare& comp = key_compare())
: c(std::move(cont)), compare(comp) { }
template<class InputIterator>
constexpr flat_set(InputIterator first, InputIterator last,
const key_compare& comp = key_compare())
: c(), compare(comp)
{ insert(first, last); }
template<class InputIterator>
constexpr flat_set(sorted_unique_t, InputIterator first, InputIterator last,
const key_compare& comp = key_compare())
: c(first, last), compare(comp) { }
template<container-compatible-range<value_type> R>
constexpr flat_set(from_range_t, R&& rg)
: flat_set(from_range, std::forward<R>(rg), key_compare()) { }
template<container-compatible-range<value_type> R>
constexpr flat_set(from_range_t, R&& rg, const key_compare& comp)
: flat_set(comp)
{ insert_range(std::forward<R>(rg)); }
constexpr flat_set(initializer_list<value_type> il, const key_compare& comp = key_compare())
: flat_set(il.begin(), il.end(), comp) { }
constexpr flat_set(sorted_unique_t s, initializer_list<value_type> il,
const key_compare& comp = key_compare())
: flat_set(s, il.begin(), il.end(), comp) { }
template<class Alloc>
constexpr explicit flat_set(const Alloc& a);
template<class Alloc>
constexpr flat_set(const key_compare& comp, const Alloc& a);
template<class Alloc>
constexpr flat_set(const container_type& cont, const Alloc& a);
template<class Alloc>
constexpr flat_set(const container_type& cont, const key_compare& comp, const Alloc& a);
template<class Alloc>
constexpr flat_set(sorted_unique_t, const container_type& cont, const Alloc& a);
template<class Alloc>
constexpr flat_set(sorted_unique_t, const container_type& cont,
const key_compare& comp, const Alloc& a);
template<class Alloc>
constexpr flat_set(const flat_set&, const Alloc& a);
template<class Alloc>
constexpr flat_set(flat_set&&, const Alloc& a);
template<class InputIterator, class Alloc>
constexpr flat_set(InputIterator first, InputIterator last, const Alloc& a);
template<class InputIterator, class Alloc>
constexpr flat_set(InputIterator first, InputIterator last,
const key_compare& comp, const Alloc& a);
template<class InputIterator, class Alloc>
constexpr flat_set(sorted_unique_t, InputIterator first, InputIterator last,
const Alloc& a);
template<class InputIterator, class Alloc>
constexpr flat_set(sorted_unique_t, InputIterator first, InputIterator last,
const key_compare& comp, const Alloc& a);
template<container-compatible-range<value_type> R, class Alloc>
constexpr flat_set(from_range_t, R&& rg, const Alloc& a);
template<container-compatible-range<value_type> R, class Alloc>
constexpr flat_set(from_range_t, R&& rg, const key_compare& comp, const Alloc& a);
template<class Alloc>
constexpr flat_set(initializer_list<value_type> il, const Alloc& a);
template<class Alloc>
constexpr flat_set(initializer_list<value_type> il, const key_compare& comp,
const Alloc& a);
template<class Alloc>
constexpr flat_set(sorted_unique_t, initializer_list<value_type> il, const Alloc& a);
template<class Alloc>
constexpr flat_set(sorted_unique_t, initializer_list<value_type> il,
const key_compare& comp, const Alloc& a);
constexpr flat_set& operator=(initializer_list<value_type>);
constexpr iterator begin() noexcept;
constexpr const_iterator begin() const noexcept;
constexpr iterator end() noexcept;
constexpr const_iterator end() const noexcept;
constexpr reverse_iterator rbegin() noexcept;
constexpr const_reverse_iterator rbegin() const noexcept;
constexpr reverse_iterator rend() noexcept;
constexpr const_reverse_iterator rend() const noexcept;
constexpr const_iterator cbegin() const noexcept;
constexpr const_iterator cend() const noexcept;
constexpr const_reverse_iterator crbegin() const noexcept;
constexpr const_reverse_iterator crend() const noexcept;
constexpr bool empty() const noexcept;
constexpr size_type size() const noexcept;
constexpr size_type max_size() const noexcept;
template<class... Args> constexpr pair<iterator, bool> emplace(Args&&... args);
template<class... Args>
constexpr iterator emplace_hint(const_iterator position, Args&&... args);
constexpr pair<iterator, bool> insert(const value_type& x)
{ return emplace(x); }
constexpr pair<iterator, bool> insert(value_type&& x)
{ return emplace(std::move(x)); }
template<class K> constexpr pair<iterator, bool> insert(K&& x);
constexpr iterator insert(const_iterator position, const value_type& x)
{ return emplace_hint(position, x); }
constexpr iterator insert(const_iterator position, value_type&& x)
{ return emplace_hint(position, std::move(x)); }
template<class K> constexpr iterator insert(const_iterator hint, K&& x);
template<class InputIterator>
constexpr void insert(InputIterator first, InputIterator last);
template<class InputIterator>
constexpr void insert(sorted_unique_t, InputIterator first, InputIterator last);
template<container-compatible-range<value_type> R>
constexpr void insert_range(R&& rg);
constexpr void insert(initializer_list<value_type> il)
{ insert(il.begin(), il.end()); }
constexpr void insert(sorted_unique_t s, initializer_list<value_type> il)
{ insert(s, il.begin(), il.end()); }
constexpr container_type extract() &&;
constexpr void replace(container_type&&);
constexpr iterator erase(iterator position);
constexpr iterator erase(const_iterator position);
constexpr size_type erase(const key_type& x);
template<class K> constexpr size_type erase(K&& x);
constexpr iterator erase(const_iterator first, const_iterator last);
constexpr void swap(flat_set& y) noexcept;
constexpr void clear() noexcept;
constexpr key_compare key_comp() const;
constexpr value_compare value_comp() const;
constexpr iterator find(const key_type& x);
constexpr const_iterator find(const key_type& x) const;
template<class K> constexpr iterator find(const K& x);
template<class K> constexpr const_iterator find(const K& x) const;
constexpr size_type count(const key_type& x) const;
template<class K> constexpr size_type count(const K& x) const;
constexpr bool contains(const key_type& x) const;
template<class K> constexpr bool contains(const K& x) const;
constexpr iterator lower_bound(const key_type& x);
constexpr const_iterator lower_bound(const key_type& x) const;
template<class K> constexpr iterator lower_bound(const K& x);
template<class K> constexpr const_iterator lower_bound(const K& x) const;
constexpr iterator upper_bound(const key_type& x);
constexpr const_iterator upper_bound(const key_type& x) const;
template<class K> constexpr iterator upper_bound(const K& x);
template<class K> constexpr const_iterator upper_bound(const K& x) const;
constexpr pair<iterator, iterator> equal_range(const key_type& x);
constexpr pair<const_iterator, const_iterator> equal_range(const key_type& x) const;
template<class K>
constexpr pair<iterator, iterator> equal_range(const K& x);
template<class K>
constexpr pair<const_iterator, const_iterator> equal_range(const K& x) const;
constexpr friend bool operator==(const flat_set& x, const flat_set& y);
constexpr friend synth-three-way-result<value_type>
operator<=>(const flat_set& x, const flat_set& y);
constexpr friend void swap(flat_set& x, flat_set& y) noexcept { x.swap(y); }
private:
container_type c;
key_compare compare;
};
template<class KeyContainer, class Compare = less<typename KeyContainer::value_type>>
flat_set(KeyContainer, Compare = Compare())
-> flat_set<typename KeyContainer::value_type, Compare, KeyContainer>;
template<class KeyContainer, class Allocator>
flat_set(KeyContainer, Allocator)
-> flat_set<typename KeyContainer::value_type,
less<typename KeyContainer::value_type>, KeyContainer>;
template<class KeyContainer, class Compare, class Allocator>
flat_set(KeyContainer, Compare, Allocator)
-> flat_set<typename KeyContainer::value_type, Compare, KeyContainer>;
template<class KeyContainer, class Compare = less<typename KeyContainer::value_type>>
flat_set(sorted_unique_t, KeyContainer, Compare = Compare())
-> flat_set<typename KeyContainer::value_type, Compare, KeyContainer>;
template<class KeyContainer, class Allocator>
flat_set(sorted_unique_t, KeyContainer, Allocator)
-> flat_set<typename KeyContainer::value_type,
less<typename KeyContainer::value_type>, KeyContainer>;
template<class KeyContainer, class Compare, class Allocator>
flat_set(sorted_unique_t, KeyContainer, Compare, Allocator)
-> flat_set<typename KeyContainer::value_type, Compare, KeyContainer>;
template<class InputIterator, class Compare = less<iter-value-type<InputIterator>>>
flat_set(InputIterator, InputIterator, Compare = Compare())
-> flat_set<iter-value-type<InputIterator>, Compare>;
template<class InputIterator, class Compare = less<iter-value-type<InputIterator>>>
flat_set(sorted_unique_t, InputIterator, InputIterator, Compare = Compare())
-> flat_set<iter-value-type<InputIterator>, Compare>;
template<ranges::input_range R, class Compare = less<ranges::range_value_t<R>>,
class Allocator = allocator<ranges::range_value_t<R>>>
flat_set(from_range_t, R&&, Compare = Compare(), Allocator = Allocator())
-> flat_set<ranges::range_value_t<R>, Compare,
vector<ranges::range_value_t<R>,
alloc-rebind<Allocator, ranges::range_value_t<R>>>>;
template<ranges::input_range R, class Allocator>
flat_set(from_range_t, R&&, Allocator)
-> flat_set<ranges::range_value_t<R>, less<ranges::range_value_t<R>>,
vector<ranges::range_value_t<R>,
alloc-rebind<Allocator, ranges::range_value_t<R>>>>;
template<class Key, class Compare = less<Key>>
flat_set(initializer_list<Key>, Compare = Compare())
-> flat_set<Key, Compare>;
template<class Key, class Compare = less<Key>>
flat_set(sorted_unique_t, initializer_list<Key>, Compare = Compare())
-> flat_set<Key, Compare>;
template<class Key, class Compare, class KeyContainer, class Allocator>
struct uses_allocator<flat_set<Key, Compare, KeyContainer>, Allocator>
: bool_constant<uses_allocator_v<KeyContainer, Allocator>> { };
}