今盒子里有n个小球，A、B两人轮流从盒中取球，每个人都可以看到另一个人取了多少个，也可以看到盒中还剩下多少个，并且两人都很聪明，不会做出错误的判断。

-This box n balls, A, B two turns from the box to take the ball, everyone can see another person take the number, you can also see the left box, and two very smart, does not make wrong judgments.