/********

have an explicit enumerator

 */

import java.util.*;

public class Sieve1 {
    private BitSet primes;

    public Sieve1(int n) {
	primes = new BitSet(n);
	for(int i = 1; i < n; i++) 
	    primes.set(i);
	for(int i = 2; i*i < n; i++)
	    if (primes.get(i))
		for(int j = 2*i; j < n; j += i)
		    primes.clear(j);
    }

    public Enumeration elements() { 
	return new SieveEnumeration();
    }

    public class SieveEnumeration implements Enumeration {
	private int index = 1;

	public boolean hasMoreElements() {
	    index++;
	    int n = primes.size();
	    while (! primes.get(index))
		if (++index > n)
		    return false;
	    return true;
	}
	
	public Object nextElement() { return new Integer(index);}
    }


    public static void main(String[] args) {
	Sieve1 p = new Sieve1(Integer.parseInt(args[0]));
	Enumeration primes = p.elements();
	while (primes.hasMoreElements())
	    System.out.println(primes.nextElement());

	primes = p.elements();
	int count = 0;
	while ((primes.hasMoreElements()) &&
	       (((Integer) primes.nextElement()).intValue() < 42))
	    count++;
	System.out.println(count + " of these primes are smaller than 42.");
    }
}