foo.cc: In function 'void dfs(int, int)':
foo.cc:17:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int j=0;j<disl[i].size();j++){
              ~^~~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:63:12: warning: unused variable 'vv' [-Wunused-variable]
  long long vv=0;
            ^~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。