foo.cc: In function ‘void ins(int)’:
foo.cc:6:20: warning: comparison of integer expressions of different signedness: ‘std::priority_queue<int, std::vector<int>, std::greater<int> >::size_type’ {aka ‘long unsigned int’} and ‘int’ [-Wsign-compare]
    6 |         if(q.size()<k) q.push(x);
      |            ~~~~~~~~^~