foo.c: In function 'main':
foo.c:16:12: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  int a1,a2;scanf("%d%d",&a1,&a2);
            ^~~~~~~~~~~~~~~~~~~~~
foo.c:19:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&a[i]);
   ^~~~~~~~~~~~~~~~~
foo.c:23:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&b[i]);
   ^~~~~~~~~~~~~~~~~

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