#M. 兔子(宜用递归)

Type: Default

1000ms

256MiB

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题目背景

小明发现青青草原上有一群兔子。

设一对兔子一个月生一对小兔子。问， $n$ 个月有多少对兔子(假设不会死亡)

一行， $n$

一行，代表 $n$ 个有后共有几只兔子

$1 <= n <= 100$