foo.c: In function 'gys':
foo.c:7:4: error: 'k' undeclared (first use in this function)
    7 |    k=m;
      |    ^
foo.c:7:4: note: each undeclared identifier is reported only once for each function it appears in
foo.c: In function 'main':
foo.c:14:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   14 |  scanf("%d",&n);
      |  ^~~~~~~~~~~~~~
foo.c:16:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   16 |   scanf("%d",&a[i]);
      |   ^~~~~~~~~~~~~~~~~

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