void sieve(deque<int>& numbers)
{
   if (numbers.empty())
      return;
   int n = numbers.front();
   numbers.pop_front();
   deque<int>::iterator p = remove_if(numbers.begin(),
      numbers.end(), DivisibleBy(n));
   numbers.erase(p, numbers.end());
   sieve(numbers);
   numbers.push_front(n);
}