题目描述

A Fibonacci sequence is calculated by adding the previous two members of the sequence, with
the first two members being both 1.
f (1) = 1, f (2) = 1, f (n > 2) = f (n − 1) + f (n − 2)
Your task is to take a number as input, and print that fibonacci number.

输入格式

100

输出格式

354224848179261915075

样例 1

输入

100

输出

354224848179261915075

提示

No generated fibonacci number in excess of 1000 digits will be in the test data, i.e. f (20) = 6765
has 4 digits.

题目来源：19 June, 2011 - Waterloo local contest；FPS 共享题包，题包内第 3 题。保留原作者与原赛事署名。