There are 15 cards, Liangliang and Dongdong take turns to draw, each round can only take 1 or 2 cards, whoever gets the last card wins. Think about it, if Dongdong wants to ensure victory, should he take the card first, or should he take the card later? How to get it? Please write it down.
有15张卡片，亮亮和东东两人轮流抽取，每轮每人只能取1张或者2张，谁取到最后一张卡片谁就赢．想一想，如果东东想确保胜利，是应该先取卡片，还是后取卡片呢？怎样取？请你写下来．
<gadget id="calculator">15 - 3 - 3 - 3 - 3</gadget>
<output>3</output>

<result>3</result>