/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:17:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0; i<mm[k].size(); i++) {
               ~^~~~~~~~~~~~~
/in/foo.cc: In function 'void bfs()':
/in/foo.cc:31:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int i=0;i<mm[u].size();i++){
                ~^~~~~~~~~~~~~