/in/foo.cc: In function 'int bfs()':
/in/foo.cc:49:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<vec[cur].size();i++)
               ~^~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:78:7: warning: unused variable 'v' [-Wunused-variable]
   int v=bfs();
       ^