foo.c: In function 'main':
foo.c:31:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf ("%d%d%d",&n1,&n2,&n3);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.c:34:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf ("%d",&p);
   ^~~~~~~~~~~~~~~
foo.c:39:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf ("%d",&q);
   ^~~~~~~~~~~~~~~
foo.c:44:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf ("%d",&o);
   ^~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务