#include <initializer_list> namespace std { template <class T, class Container = deque<T>> class stack; template <class T, class Container> bool operator==(const stack<T, Container>& x, const stack<T, Container>& y); template <class T, class Container> bool operator< (const stack<T, Container>& x, const stack<T, Container>& y); template <class T, class Container> bool operator!=(const stack<T, Container>& x, const stack<T, Container>& y); template <class T, class Container> bool operator> (const stack<T, Container>& x, const stack<T, Container>& y); template <class T, class Container> bool operator>=(const stack<T, Container>& x, const stack<T, Container>& y); template <class T, class Container> bool operator<=(const stack<T, Container>& x, const stack<T, Container>& y); template <class T, class Container> void swap(stack<T, Container>& x, stack<T, Container>& y) noexcept(noexcept(x.swap(y))); }