题解 | 汽水瓶

d=[]
while True:
    line =int(input())# 只读取一次
    if not line:  # 空行就退出
        break
    d.append(line)
def f(z):
    oo=0
    while z>3:
        d=z % 3 +z //3
        oo=oo+z//3
        z=d
    else:
        oo+=1
    return oo

for i in range(len(d)):
    if d[i] == 0 :
        pass
    elif d[i] ==  1:
        print(0)
    else:
        print(f(d[i]))