题目描述
A Fibonacci sequence is calculated by adding the previous two members of the sequence, with
the rst 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 bonacci number.
提示
No generated bonacci number in excess of 1000 digits will be in the test data, i.e. f(20) = 6765 has 4 digits.