public class Node
{
	protected int data;
	protected Node prev;
	protected Node next;
	public Node(int data)
	{
		this.data = data;
		prev = null;
		next = null;
	}
	public Node(int data, Node prev, Node next)
	{
		this.data = data;
		this.prev = prev;
		this.next = next;
	}
	public int getData()
	{
		return data;
	}
	public void setData(int data)
	{
		this.data = data;
	}
	public Node getPrev()
	{
		return prev;
	}
	public void setPrev(Node prev)
	{
		this.prev = prev;
	}
	public Node getNext
	{
		return next;
	}
	public void setNext(Node next)
	{
		this.next = next;
	}
}
public class DLL
{
	protected Node head;
	protected Node tail;
	int length;
	public DLL()
	{
		head = new Node(Integer.MIN_VALUE,null,null);
		tail = new Node(Integer.MIN_VALUE,null,null);
		head.setNext(tail);
		length = 0;
	}
}


a)

public void insertRear(int data)
{
	Node node = new Node(data,tail.getPrev(),tail);
	node.getPrev().setNext(node);
	tail.setPrev(node);
	length++;
}

b)

public void insertRear(int data)
{
	Node node = new Node(data,tail.getPrev(),tail);
	node.getPrev().getPrev().setNext(node);
	tail.setPrev(node);
	length++;
}

c)

public void insertRear(int data)
{
	Node node = new Node(data,tail.getPrev(),tail);
	node.getPrev().setNext(tail);
	tail.setPrev(node);
	length++;
}

d)

public void insertRear(int data)
{
	Node node = new Node(data,head,tail);
	node.getPrev().setNext(node);
	tail.setPrev(node);
	length++;
}