I just use two lines in my code.

pos=(pos+N-1)%question.length();
question.erase(pos,1);

and I got AC...

though it is a bit slow.
But still unbelievable.

It is Josephus problem...
Change your solution:

for(int len = question.length(); len>0; len--)
  pos = (pos+ N-1)%len;
printf("%d", question[pos]);

What does "Orz C++" stand for?

cool. you don't need to delete the character in each loop