//WAJ to demo Treeset
import java.util.*;
public class TestJavaCollection9b{
    public static void main(String args[]){
    TreeSet<String> set=new TreeSet<String>();
    set.add("Ravi");
    set.add("Vijay");
    set.add("");
    set.add(null);
    set.add("Ravi");
    set.add("Ajay");

    Iterator<String> itr=set.iterator();
    while(itr.hasNext()){
    System.out.println(itr.next());
    }
    }
}