/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:31:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (tmp.size() < min_cnt) {
       ~~~~~~~~~~~^~~~~~~~~
/in/foo.cc:40:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < op[no].size(); j++) {
                   ~~^~~~~~~~~~~~~~~
/in/foo.cc:46:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < op[no].size(); j++) {
                   ~~^~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:61:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < ans.size(); i++) {
                  ~~^~~~~~~~~~~~