foo.cc: In function 'int main()':
foo.cc:48:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &a1, &n1);
  ~~~~~^~~~~~~~~~~~~~~~~~
foo.cc:54:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &a2, &n2);
  ~~~~~^~~~~~~~~~~~~~~~~~

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