template<class T, class U>
bool operator<(const pair<T, U>& x, const pair<T, U>& y);
template<class T, class U>
bool operator<(const pair<T, U>& x, const pair<T, U>& y);
The template function returns x.
first
< y.first || !(y.first < x.first && x.
second
< y.second
.
See the related sample program.