题解 | 汽水瓶

x = []
# 输入读取
while 1:
    X = int(input())
    if X == 0:
        break
    x.append(X)
# 输出结果初始化
y = []
# 循环计算
for i in range(len(x)):
    X = x[i]
    Y = 0 # 初始计数
    YY = X # 空瓶
    while 1:# 循环兑换，每次一轮
        # 兑换
        if YY < 3: # 兑换暂停条件
            break
        Y += int(YY/3) # 兑换增量
        YY = YY % 3 + int(YY/3) # 下一轮空瓶
    # 输出结果保存
    if YY < 2:
        y.append(Y)
    else:
        y.append(Y+1) # 借空瓶多兑一瓶
# 结果输出
for i in range(len(y)):
    print(y[i])