foo.cc: In function 'int unionSet(int*, int, int*, int, int*)':
foo.cc:41:13: warning: unused variable 'index' [-Wunused-variable]
  int i,n3=0,index=0;
             ^~~~~
foo.cc: In function 'int main()':
foo.cc:54:15: warning: unused variable 'i' [-Wunused-variable]
  int n1,n2,n3,i;
               ^

[Hydro](https://hydro.ac)提供评测服务