foo.cc: In function 'int main()':
foo.cc:23:7: warning: unused variable 'i' [-Wunused-variable]
  ll m,i,j;
       ^
foo.cc:23:9: warning: unused variable 'j' [-Wunused-variable]
  ll m,i,j;
         ^

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