foo.cc: In function 'int main()':
foo.cc:22:8: warning: unused variable 'i' [-Wunused-variable]
  int m,i,j;
        ^
foo.cc:22:10: warning: unused variable 'j' [-Wunused-variable]
  int m,i,j;
          ^

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