foo.c: In function 'main':
foo.c:12:6: warning: unused variable 'k' [-Wunused-variable]
   12 |  int k;
      |      ^
foo.c:5:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    5 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
foo.c:6:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    6 |  scanf("%d", &m);
      |  ^~~~~~~~~~~~~~~

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