foo.cc: In function 'int main()':
foo.cc:8:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &x1, &n1);
  ~~~~~^~~~~~~~~~~~~~~~~~
foo.cc:9:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &x2, &n2);
  ~~~~~^~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务