foo.cc: In function 'int main()':
foo.cc:10:18: warning: 'n1' is used uninitialized in this function [-Wuninitialized]
     for(int i=0;i<n1;i++)
                 ~^~~
foo.cc:9:18: warning: 'n2' may be used uninitialized in this function [-Wmaybe-uninitialized]
     int b[10000],n2;
                  ^~

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