foo.cc: In function 'int main()':
foo.cc:9:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d %d %d",&n,&m,&r,&c);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:14:41: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(i=0;i<n;i++) for(j=0;j<m;j++) scanf("%d",&v[i][j]);
                                    ~~~~~^~~~~~~~~~~~~~~

自豪的采用 HydroJudger 进行评测(github.com/hydro-dev/HydroJudger)

{"receive":"2020-05-28T09:48:15.864Z","handle":"2020-05-28T09:48:15.864Z","cache_start":"2020-05-28T09:48:15.871Z","read_cases":"2020-05-28T09:48:16.439Z","judge":"2020-05-28T09:48:16.440Z","done":"2020-05-28T09:48:20.221Z"}