# 20240911
def f(n):
    if n == 1:
        return 0
    elif n == 0:
        return 0
    else:
        return 1+f(n-2)   # 这里运用了递归函数
    
while True:
    try:
        n = int(input())
        if n == 0:
            break
        print(f(n))
    except:
        break