/in/foo.cc: In function 'void Solve()':
/in/foo.cc:30:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0; i<ans.size(); i++)
               ~^~~~~~~~~~~
/in/foo.cc:32:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(res.size() == i) res.push_back(0);
      ~~~~~~~~~~~^~~~
/in/foo.cc:51:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0; i<res.size(); i++)
                ~^~~~~~~~~~~