/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:65:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < Nd.size(); i++) {
                 ~~^~~~~~~~~~~
/in/foo.cc:71:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   printf(i < Nd.size() - 1 ? "%d " : "%d", Nd[i].second);
          ~~^~~~~~~~~~~~~~~