import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
public class Main {
public static void main(String[] args) {
HashSet hashSet = new HashSet();
hashSet.add("A");
hashSet.add("B");
hashSet.add("D");
hashSet.add("E");
hashSet.add("F");
Enumeration e = Collections.enumeration(hashSet);
while (e.hasMoreElements())
System.out.println(e.nextElement());
}
}