foo.cc: In function 'int main()':
foo.cc:7:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    7 |     scanf("%d", &k);
      |     ~~~~~^~~~~~~~~~
foo.cc:10:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   10 |         scanf("%d%d", &n, &f);
      |         ~~~~~^~~~~~~~~~~~~~~~
foo.cc:12:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   12 |             scanf("%d", &a);
      |             ~~~~~^~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务