public static Node FindNthLast(Node head,int n){
		Node p = head.next;
		Node q = head.next;
		while(true){
			if(n == 0){
				break;
			}
			if(q==null)
				return null;
			q = q.next;
			n--;
		}
		while(q!=null){
			q = q.next;
			p = p.next;
		}
		return p;
		
	}