编辑代码

# coding:utf-8
#JSRUN引擎2.0，支持多达30种语言在线运行，全仿真在线交互输入输出。
#class solution:
#    def getnum(self, n:int) -> int:

b1 = 1
b2 = 1
b3 = 1
b = 0
#MONTH = int(input())
MONTH = 20
for i in range(0,MONTH):
    if (i == 0 or i== 1 or i == 2):
        b3 = 1
    else:
        b = b3
        b3 = b1 + b3
        b1 = b2
        b2 = b
    
print (2*b3)