foo.cc: In function 'int main()':
foo.cc:24:6: warning: unused variable 'i' [-Wunused-variable]
   24 |  int i,j;
      |      ^
foo.cc:24:8: warning: unused variable 'j' [-Wunused-variable]
   24 |  int i,j;
      |        ^

[Hydro](https://hydro.ac)提供评测服务