/in/foo.cc: In member function 'void F::bfs()':
/in/foo.cc:87:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int i=0;i<v[x].size();++i){
                         ~^~~~~~~~~~~~
/in/foo.cc: In member function 'long long int F::dfs(int, long long int)':
/in/foo.cc:95:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(;i[x]<v[x].size();++i[x]){
              ~~~~^~~~~~~~~~~~