foo.cc: In function 'int main()':
foo.cc:9:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    9 |     scanf("%d%lld",&n,&m);
      |     ~~~~~^~~~~~~~~~~~~~~~
foo.cc:10:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   10 |     for(i=1;i<=n;i++) scanf("%d",&a[0][i]),a[0][i]--;
      |                       ~~~~~^~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务