foo.cc: In function 'int main()':
foo.cc:5:14: warning: unused variable 'a' [-Wunused-variable]
  long long b,a,year;;cin>>b;
              ^
foo.cc:5:16: warning: unused variable 'year' [-Wunused-variable]
  long long b,a,year;;cin>>b;
                ^~~~

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