Set

import java.util.HashSet;
import java.util.Set;
import java.util.Iterator;
public class Main{
    public static void main(String args[]){
        Set s = new HashSet();
        for(int i=5;i>=0;i--) s.add(new Integer(i));
        System.out.println(s.size());
        System.out.println(s.isEmpty());
        Iterator it = s.iterator();
        while(it.hasNext()){
            System.out.println(it.next());
        }
        s.clear();
        System.out.println(s.size());
        System.out.println(s.isEmpty());
    }
}