foo.cc: In function 'int main()':
foo.cc:6:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
     freopen("test1.in","r",stdin);
     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
foo.cc:7:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
     freopen("test1.out","w",stdout);
     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:8:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d",&n,&m,&t);
  ~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:9:49: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i=1;i<=n;i++)for(int j=1;j<=m;j++)scanf("%d",&a[i][j]);
                                            ~~~~~^~~~~~~~~~~~~~~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。