foo.cc: In function 'int main()':
foo.cc:55:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d",&n1,&x1);
  ~~~~~^~~~~~~~~~~~~~~~~
foo.cc:56:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d",&n2,&x2);
  ~~~~~^~~~~~~~~~~~~~~~~

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