/in/foo.cc: In function 'void bfs()':
/in/foo.cc:26:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0; i < s[now].size(); ++i){
                  ~~^~~~~~~~~~~~~~~
/in/foo.cc:24:7: warning: unused variable 'cnt' [-Wunused-variable]
   int cnt = 0;
       ^~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:52:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < ans.size(); ++i){
                 ~~^~~~~~~~~~~~