/in/foo.cc: In function 'int main()':
/in/foo.cc:54:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < Md.size(); i++) {
                 ~~^~~~~~~~~~~
/in/foo.cc:60:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   printf(i == Md.size() - 1 ? "%d" : "%d ", Md[i].second);
          ~~^~~~~~~~~~~~~~~~
/in/foo.cc:67:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < Nd.size(); i++) {
                 ~~^~~~~~~~~~~
/in/foo.cc:73:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   printf(i == Nd.size() - 1 ? "%d" : "%d ", Nd[i].second);
          ~~^~~~~~~~~~~~~~~~