set comparator

#include <iostream>
#include <set>
#include <functional>

int main() {
    std::set<int, std::function<bool(int, int)>> s([](int l, int r) {
                                                       return l > r;
                                                   });
    s.insert(1);
    s.insert(2);
    std::cout << *s.cbegin() << std::endl;
    return 0;
}