foo.cc: In function 'int main()':
foo.cc:6:25: warning: unused variable 'cnt1' [-Wunused-variable]
  long long n;cin>>n;int cnt1=0,cnt2=0;
                         ^~~~
foo.cc:6:32: warning: unused variable 'cnt2' [-Wunused-variable]
  long long n;cin>>n;int cnt1=0,cnt2=0;
                                ^~~~

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