foo.cc: In function 'int main()':
foo.cc:8:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    8 |     scanf("%d%d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~
foo.cc:11:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   11 |         scanf("%d", a + i);
      |         ~~~~~^~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务