foo.cc: In function 'void solve()':
foo.cc:42:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lf%lf",&x[i],&y[i]);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:51:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%lf",&n,&r);
     ~~~~~^~~~~~~~~~~~~~~

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