public class LinkedList {

	private Node head;
	private Node tail;
	private int size;
	
	
	public LinkedList() {
		head = tail = null;
		size = 0;
	}
 	
	public void insertAtHead(Object data) {		
		Node n = new Node(data);
		if(size == 0) {
			head = n;
			tail = n;
		} else {
			n.setNext(head);
			head = n;
		}
		size++;
	}
	
	public void insertAtTail(Object data) {
		Node n = new Node(data);
		if(size == 0) {
			head = tail = n;
		} else {
			tail.setNext(n);
			tail = n;
		}
		size++;
	}
	
	public void deleteHead() {
		if(size == 0) {
			System.err.println("No head node to delete");
			return;
		}
		head = head.getNext();
		size--;
	}
	
	public void deleteTail() {
		if(size == 0) {
			System.err.println("No tail node to delete");
			return;
		} else if(size == 1) {
			head = tail = null;
			size--;
			return;
		}
		Node i = head;
		while(i.getNext() != tail) {
			i = i.getNext();
		}
		i.setNext(null);
		tail = i;
		size--;
	}
	
	
	public void print() {
		Node i = head;
		
		while(i != null) {
			i.print();
			i = i.getNext();
		}
	}
	
	
	
	
}