/in/foo.cc: In function 'void dfs_(int, int, int)':
/in/foo.cc:12:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<G[v].size();i++)
                 ~^~~~~~~~~~~~
/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:66:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<G[now].size();i++){
              ~^~~~~~~~~~~~~~