/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:27:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<a[tot].size();i++){
              ~^~~~~~~~~~~~~~
/in/foo.cc:26:6: warning: unused variable 'k' [-Wunused-variable]
  int k=totd;
      ^