foo.c: In function 'main':
foo.c:8:9: warning: zero-length gnu_printf format string [-Wformat-zero-length]
  printf("");
         ^~
foo.c:13:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&num1,&num2);
  ^~~~~~~~~~~~~~~~~~~~~~~~~

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