import java.util.*;

class ClassA implements Comparable<ClassA> {
	private int value;

	ClassA(int value){
		this.value = value;
	}
	public int compareTo(ClassA ca){
		return value - ca.value;
	}
	@Override
	public int hashCode(){
		return value;
	}
	@Override
	public boolean equals(Object o){
		return value == ((ClassA)o).value;
	}
	public int getValue(){
		return value;
	}
}

class Reverse {
	static Comparator<T extends Comparable<T>> reverseOrder(){
		return new Comparator<T>(){
			public int compare(T o1, T o2){
				return o2.compareTo(o1);
			}
		};
	}
}

class Samp19 {
	public static void main(String[] args){
		Comparator<ClassA> ca = Reverse.reverseOrder();
		System.out.println(ca.getClass().getName());
		TreeSet<ClassA> tsa = new TreeSet<ClassA>(ca);
		tsa.add(new ClassA(30));
		tsa.add(new ClassA(20));
		tsa.add(new ClassA(10));
		for(ClassA c: tsa){
			System.out.println(c.getValue());
		}
	}
}