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("%lld%lld", &n, &k);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务