operator>

template<class Key, class Pred, class A>
    bool operator>(
        const set <Key, Pred, A>& lhs,
        const set <Key, Pred, A>& rhs);
template<class Key, class Pred, class A>
    bool operator>(
        const multiset <Key, Pred, A>& lhs,
        const multiset <Key, Pred, A>& rhs);