/in/foo.cc: In function 'int main()':
/in/foo.cc:40:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (Heap.size() > k) Heap.pop();
       ~~~~~~~~~~~~^~~
/in/foo.cc:41:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (Heap.size() == k && Heap.top() - a[i].val.first > ans) {
       ~~~~~~~~~~~~^~~~