foo.cc: In function 'int main()':
foo.cc:10:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d",&n,&m);
     ~~~~~^~~~~~~~~~~~~~~
foo.cc:16:15: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf ("%d %d",&x,&y);
         ~~~~~~^~~~~~~~~~~~~~~
foo.cc:22:15: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf ("%d %d",&x,&y);
         ~~~~~~^~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务