namespace std {
    namespace rel_ops {
        template <class T>
        inline bool operator != (const T& x, const T& y) {
            return !(x == y);
        }

        template <class T>
        inline bool operator> (const T& x, const T& y) {
            return y < x;
        }

        template <class T>
        inline bool operator<= (const T& x, const T& y) {
            return !(y < x);
        }

        template <class T>
        inline bool operator>= (const T& x, const T& y) {
            return !(x < y);
        }
    }
}