foo.cc: In function 'int main()':
foo.cc:10:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   10 |  scanf("%d%d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~
foo.cc:13:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   13 |    scanf("%lld", &a[i][j]);
      |    ~~~~~^~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务