foo.cc: In function 'int main()':
foo.cc:39:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 if (v.size()==n) break;
                     ~~~~~~~~^~~
foo.cc:54:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i=0;i<v.size();i++) cout<<v[i]<<" ";
                      ~^~~~~~~~~

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