foo.cc: In function 'int main()':
foo.cc:12:13: warning: unused variable 'i' [-Wunused-variable]
   12 |         int i;
      |             ^
foo.cc: In function 'int add(int*, int, int*, int)':
foo.cc:23:20: warning: unused variable 'j' [-Wunused-variable]
   23 |         int i = 0, j = 0;
      |                    ^

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