foo.c: In function 'main':
foo.c:9:24: warning: unused variable 'mark' [-Wunused-variable]
    9 |  int gcb = 1, lcm = 1, mark;
      |                        ^~~~
foo.c:10:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   10 |  scanf("%d", &k);
      |  ^~~~~~~~~~~~~~~
foo.c:12:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   12 |   scanf("%d", &n);
      |   ^~~~~~~~~~~~~~~

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