foo.cc: In function 'int main()':
foo.cc:9:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    9 |  scanf("%d%d",&n,&m);
      |  ~~~~~^~~~~~~~~~~~~~
foo.cc:12:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   12 |   scanf("%d",&a[i]);
      |   ~~~~~^~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务