题解 | #汽水瓶#python3递归

total = 0
def fun(num):
    global total
    if num <2:
        print(total)
        return 0
    elif num ==2:
        
        total +=1
        print(total)
    else:
        nn = num // 3
        total += nn
        left = nn + num % 3

        fun(left)

while True:
    try:
        num = int(input())
        total = 0
        if num != 0:
            fun(num)
    except:
        break