public class LinkedList {

	private ListNode head;
	private ListNode tail;
	
	LinkedList()
	{
		head = new ListNode(null);
		tail = head;
	}
	
/**
 * Add an element to the end of the list
 * @param o The object to add to the end of the list
 */
    public void add(Object o)
    {
    	tail.setNext(new ListNode(o));
    	tail = tail.next();
    }
    
    /**
     * Remove the first occurrence of elemToRemove from the list.  If elemToRemove does not
     * appear in the list, then do nothing.
     * @param elemToRemove The element to remove from the list
     */
    public void removeFirst(Object elemToRemove)
    {
	// TODO:  FILL BE IN!
    }
    
    /**
     * Remove all occurrences of an element from a list.
     * @param elemToRemove The element to remove from the list
     */
    public void removeAll(Object elemToRemove)
    {
	// TODO:  FILL BE IN!
    }
        
    /**
     * Remove the last occurrence of an element from a list.
     * @param elemToRemove The element to remove from the list
     */
    public void removeLast(Object elemToRemove)
    {
	// TODO:  FILL BE IN!
    }
    
    /**
     * Create a string representation of the list.  The created string will begin with '[' and
     * end with ']', and contain the toString representation of all elements in the list,
     * separated by commas.  So, if the list contains the first 3 positive integers, then
     * toString would return the string "[1, 2, 3]"
     */
    public String toString()
    {
	// TODO:  FILL BE IN!
        return "";  // Just so this will compile
    }
    
    
    
    public static void main(String args[])
    {

    	LinkedList L  = new LinkedList();
    	for (int i = 0; i < 4; i++)
    	{
    		for (int j = 0; j < 5; j++)
    		{
    			L.add(j);
    		}
    	}
    	System.out.println(L);
    	L.removeFirst(1);
    	System.out.println(L);
    	L.removeFirst(0);
    	System.out.println(L);
    	L.removeLast(3);
    	System.out.println(L);
    	L.removeLast(4);
    	System.out.println(L);
    	L.add(5);
    	System.out.println(L);
    	L.removeAll(0);
    	System.out.println(L);
    	L.removeAll(5);
    	System.out.println(L);

    	L = new LinkedList();
    	for (int i = 0; i < 10; i++)
    	{
    		L.add(1);
    	}
    	System.out.println(L);
    	L.removeAll(1);
    	System.out.println(L);
    	L.add(2);
    	System.out.println(L);
    }



}