public NodeDLL deletekey(int key)
	{
		NodeDLL current = first;
		while(current.data != key)
		{
			current = current.next;
		}
		if (first == null)
		{
			return null;
		}
		
		if(current == first)
		{
			first = current.next;
		}
		else
		{
			current.previous.next = current.next;
		}
		
		if(current == last)
		{
			last = current.previous;
		}
		else
		{
			current.next.previous = current.previous;
		}
		
		return current;
	}