vector pair sort first element inc. second dec.

struct Comp {
  bool operator()(const std::pair<int, int> &a, const std::pair<int, int> &b) {
    if (a.first != b.first) {
      return a.first < b.first;
    }
    return a.second > b.second;
  }

};

Comp comp_functor;
std::sort(myVec.begin(), myVec.end(), comp_functor);