namespace std { template<class charT, class traits = char_traits<charT>> class basic_ostream; using ostream = basic_ostream<char>; using wostream = basic_ostream<wchar_t>; template<class charT, class traits> basic_ostream<charT, traits>& endl(basic_ostream<charT, traits>& os); template<class charT, class traits> basic_ostream<charT, traits>& ends(basic_ostream<charT, traits>& os); template<class charT, class traits> basic_ostream<charT, traits>& flush(basic_ostream<charT, traits>& os); template<class charT, class traits> basic_ostream<charT, traits>& emit_on_flush(basic_ostream<charT, traits>& os); template<class charT, class traits> basic_ostream<charT, traits>& noemit_on_flush(basic_ostream<charT, traits>& os); template<class charT, class traits> basic_ostream<charT, traits>& flush_emit(basic_ostream<charT, traits>& os); template<class charT, class traits, class T> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>&& os, const T& x); }