foo.cc: In function 'int main()':
foo.cc:37:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   37 |     scanf("%d%d", &n, &k);
      |     ~~~~~^~~~~~~~~~~~~~~~
foo.cc:39:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   39 |         scanf("%d", &a[i]);
      |         ~~~~~^~~~~~~~~~~~~
foo.cc:41:11: warning: ignoring return value of 'int system(const char*)', declared with attribute warn_unused_result [-Wunused-result]
   41 |     system("pause");
      |     ~~~~~~^~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务