©TCP-tryJAVA

import java.util.*;

class DescendingOrder implements Comparator<Integer> {
	public int compare(Integer o1, Integer o2) {
		if(o1 instanceof Comparable && o2 instanceof Comparable) {
			Integer c1 = (Integer)o1;
			Integer c2 = (Integer)o2;
			return c2.compareTo(c1);
		}
		return -1;
	}
}

public class prog {
	public static void main(String[] args) {
		TreeSet<Integer> ts = new TreeSet<Integer>(new DescendingOrder());
		
		ts.add(30);
		ts.add(40);
		ts.add(20);
		ts.add(10);
		
		Iterator<Integer> iter = ts.iterator();
		while(iter.hasNext()) {
			System.out.println(iter.next());
		}
	}
}