There are 25 marked chips, each of which is marked with a different odd number from 1 to 49, and two people take turns to choose chips. When one person chooses the chip labeled x, the other person must choose the chip labeled (99-x) with the largest odd factor. If the number of the first selected chip is 5, then when the game is over, how many chips are left.
设有25个标号筹码，其中每个筹码都标有从1到49中的一个不同的奇数，两个人轮流选取筹码．当一个人选取了标号为x的筹码时，另一个人必须选取标号为(99-x)的最大奇因数的筹码．如果第一个被选取的筹码的编号为5，那么当游戏结束时，还剩多少个筹码．
<gadget id="calculator">25 - 7</gadget>
<output>18</output>

<result>18</result>