There are 21 cards, two people take turns to take cards, each time can only take 1 or 2 cards, whoever gets the last card will win. Think about it, if you want to ensure that you win, should you take the card first or should you take the card last? how to get it
有21张牌，两人轮流拿牌，每次只能拿1或2张牌，谁拿到最后一张牌谁就获胜．想一想，如果你为了确保获胜，你应该先拿牌还是应该后拿牌？怎样拿？
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