foo.cc: In function 'long long int erfen(double)':
foo.cc:14:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   int mid=L+R>>1;
           ~^~
foo.cc: In function 'int main()':
foo.cc:25:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld%lld",&n,&s);
  ~~~~~^~~~~~~~~~~~~~~~~~
foo.cc:27:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld%lld",&x,&y);
   ~~~~~^~~~~~~~~~~~~~~~~~

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

{"receive":"2020-07-10T06:02:40.752Z","handle":"2020-07-10T06:02:40.752Z","cache_start":"2020-07-10T06:02:40.759Z","read_cases":"2020-07-10T06:02:40.891Z","judge":"2020-07-10T06:02:40.892Z","done":"2020-07-10T06:02:42.111Z"}