foo.cc: In function 'int main()':
foo.cc:5:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    5 |  scanf("%d%d",&n,&m);
      |  ~~~~~^~~~~~~~~~~~~~
foo.cc:9:38: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    9 |   for(register int j=1;j<=m;++j)scanf("%d",&a[i][j]);
      |                                 ~~~~~^~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务