foo.c: In function 'main':
foo.c:5:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    5 |  scanf("%d%d",&m,&n);
      |  ^~~~~~~~~~~~~~~~~~~
foo.c:8:4: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    8 |    scanf("%d",&a[i][j]);
      |    ^~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务