foo.cc: In function 'int main()':
foo.cc:10:16: warning: unused variable 'j' [-Wunused-variable]
   10 |  int em, n, i, j, k, ans = 0;
      |                ^
foo.cc:10:19: warning: unused variable 'k' [-Wunused-variable]
   10 |  int em, n, i, j, k, ans = 0;
      |                   ^

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