/in/foo.cc:6:27: warning: 'ans' defined but not used [-Wunused-variable]
 static int prime[S],sum=0,ans=0;
                           ^~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:33:13: warning: iteration 31998 invokes undefined behavior [-Waggressive-loop-optimizations]
   if (!jud[i]) 
        ~~~~~^
/in/foo.cc:31:16: note: within this loop
  for (int i=2;i<=n;i++)
               ~^~~