题解 | #汽水瓶#笨办法

def drink (x):
    d=0
    while x >= 2:
        if x==2:
            d+=1
            break
        else:
            x-=3
            d+=1
            x+=1
    return d

t=[]
while True:
    a=int(input())
    if a==0:
        break
    else:
        t.append(a)

for i in t:
    print(drink(i))