foo.c: In function 'main':
foo.c:4:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  int n; scanf("%d", &n);
         ^~~~~~~~~~~~~~~
foo.c:6:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &a[0]);
  ^~~~~~~~~~~~~~~~~~
foo.c:9:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &a[i]);
   ^~~~~~~~~~~~~~~~~~

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