foo.cc: In function 'int main()':
foo.cc:14:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   14 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
foo.cc:17:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   17 |         scanf("%lld%lld%lld%lld",&a0,&a1,&b0,&b1);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务