foo.cc: In function 'int main()':
foo.cc:8:24: warning: unused variable 'c' [-Wunused-variable]
  int a[10005],b[10005],c[10005],d[10005],n1,n2,n3;
                        ^
foo.cc:8:48: warning: unused variable 'n3' [-Wunused-variable]
  int a[10005],b[10005],c[10005],d[10005],n1,n2,n3;
                                                ^~

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