foo.c: In function 'main':
foo.c:15:10: warning: unused variable 'k' [-Wunused-variable]
   15 |  int i,n,k,a[100],s;
      |          ^
foo.c:16:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   16 |  scanf("%d",&n);
      |  ^~~~~~~~~~~~~~
foo.c:18:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   18 |   scanf("%d",&a[i]);
      |   ^~~~~~~~~~~~~~~~~

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