题解 | #统计每个月兔子的总数#
统计每个月兔子的总数
https://www.nowcoder.com/practice/1221ec77125d4370833fd3ad5ba72395
n = int(input())
# 设出生1天的兔子有n1只，出生2天的兔子有n2只，成熟的兔子有m只
n1 = 1
n2 = 0
m = 0
total = 1
i = 1
while i < n:
m += n2
lastN1 = n1
n1 = m
n2 = lastN1
i += 1
total = n1 + n2 + m
print(total)
