foo.cc: In function 'int main()':
foo.cc:6:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &m, &n);
  ~~~~~^~~~~~~~~~~~~~~~
foo.cc:9:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d", &Mat[i][j]);
    ~~~~~^~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务