# -- coding: utf-8 --

# 斐波那契数列
class solution:
    def Fibonacci( n):
        a,b=0,1

        while n:
            c=a+b
            a=b
            b=c
            n-=1
        return a

    def Fibonacci_2(self,n):
        if n<=0:
            return 0
        if n==1 or n==2:
            return 1
        else:
            return self.Fibonacci(n-1)+self.Fibonacci(n-2)