题目描述 The Fibonacci Numbers $ \{0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55...\} $ are defined by the recurrence: $ F 0 = 0 $ $ F 1 = 1 $ $ F n = F {n-1} + F {n-2}, n >= 2 $ Write a program to calculate the Fibonacci Numbers. 输入格式 Each case contains a number $ n $ and you are expected to calculate $ F n $ $(0 <= n <= 30)$. 输出格式 For each case, print a number $ F n $ on a separate line, which means the $ n $th Fibonacci Number. 输入样例 1 输出样例 1