题解 | #统计每个月兔子的总数#

#用到了递归函数，其中要注意全局变量的定义
def accrue(month, n, num1):
    global i
    for i in range(month + 2, n + 1):
        num1 = num1 +1
        num1 = accrue(i, n, num1)
    return num1


while True:
    try:
        n = int(input())
        num = accrue(1, n, 1)
        print(num)
    except:
        break