public class DoubleList {

	private int size;
	private Node header;
	private Node trailer;
	
	public DoubleList() {
		size = 0;
		header = new Node(null);
		trailer = new Node(null);
		header.setNext(trailer);
		trailer.setPrev(header);	
	}	
	
	public void insertAtHead(Object data) {
		Node n = new Node(data);
		
		n.setNext(header.getNext());
		n.setPrev(header);
		header.setNext(n);
		n.getNext().setPrev(n);
		size++;	
	}
	
	public void deleteHead() {
		if(size == 0) {
			return;
		}
		header.setNext(header.getNext().getNext());
		header.getNext().setPrev(header);
	}
	
	
	
	public void print() {
		
		Node tmp = header.getNext();
		
		while(tmp.getNext() != null) {
			tmp.print();
			tmp = tmp.getNext();
		}
		
	}
	
	
	
}