/in/foo.cc: In function 'int main()':
/in/foo.cc:33:18: warning: iteration 30 invokes undefined behavior [-Waggressive-loop-optimizations]
   if(maxn<Hash2[i] && Hash2[i]!=0)maxn=Hash2[i];
           ~~~~~~~^
/in/foo.cc:30:15: note: within this loop
  for(int i=0;i<=30;i++)
              ~^~~~