import java.util.*;

public class LinkedList implements List
{
   Node head;
   Node tail;

   public void addFirst(Object o)
   {
   } // addFirst

   public void addAfter(Object newO, Object after)
   {
   } // addAfter

   public void add(Object o)
   {
      Node newNode = new Node(o);

      if (head == null)
	 tail = head = newNode;
      else
	 tail = tail.next = newNode;
   } // add

   public void delete(Object o){}

   public boolean find(Object o)
   {
      Node current = head;

      while (current != null)
      {
	 if (current.data.equals(o))
	    return true;
	 current = current.next;
      } // while
      return false;
   } // find

   public void print()
   {
      Node current = head;

      while (current != null)
      {
	 System.out.println(current.data);
	 current = current.next;
      } // while
   } // print

   public Enumeration elements()
   {
      return new ListEnumeration();
   } // elements

   private class ListEnumeration implements Enumeration
   {
      Node current = head;

      public boolean hasMoreElements()
      {
	 if (current == null)
	    return false;
         return true;
      } // hasMoreElements

      public Object nextElement()
      {
	 Object theNext = current.data;

	 current = current.next;
	 return theNext;
      } // nextElement
   } // class ListEnumeration

   private class Node
   {
      Object data;
      Node next;

      Node(Object o, Node n)
      {
	 data = o;
	 next = n;
      } // constructor

      Node(Object o)
      {
	 data = o;
      } // constructor
   } // class Node
} // class LinkedList