The game starts at the root with no number eliminated. You get first move. You may choose or , then or , and so on. Before making a move, you first must ask your adversary whether he wants to choose (unless he has already chosen twice in a row). If he does not, you can choose. Your aim is to get as high a number as possible. The aim of your adversary is that you get as small a number as possible. Without an adversary, you can play for both sides.