foo.cc: In function 'int main()':
foo.cc:17:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   17 |     scanf("%d%d%d%d",&m,&n,&kk,&ll);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:21:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   21 |             scanf("%d",&t[i][j]);
      |             ~~~~~^~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务