/in/foo.cc: In function 'int DFS(int)':
/in/foo.cc:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int z = 0; z < edge[x].size(); z++)
                     ~~^~~~~~~~~~~~~~~~
/in/foo.cc:38:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^