/in/foo.cc: In function 'bool ok(int, int)':
/in/foo.cc:13:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<tmp.size();i++) {
              ~^~~~~~~~~~~
/in/foo.cc:14:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<v[tmp[i]].size();j++) {
               ~^~~~~~~~~~~~~~~~~