foo.c: In function 'main':
foo.c:22:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &m, &n);
  ^~~~~~~~~~~~~~~~~~~~~
foo.c:26:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &a[i]);
   ^~~~~~~~~~~~~~~~~~
foo.c:30:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &b[i]);
   ^~~~~~~~~~~~~~~~~~

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