# 2021级《程序设计原理及C语言》练习题

E. Fibonacci sequence

Input an integer $n$ ($0 \le n \le 64$), output nth item in the Fibonacci sequence in one line.

The Fibonacci sequence starts with $0$ and $1$, and all following items are sum of their previous two items.

### 样例

Input
0

Output
0

Input
30

Output
832040


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