题解 | 汽水瓶
def ex(n):
if n == 2:
return 1
if n == 1:
return 0
if n == 0:
return 0
y = n//3
a = n-3*y
b = y+a
return y + ex(b)
while True:
n = eval(input())
if n == 0:
break
if n > 2:
n=ex(n)
print(n)
