while True:
    count_digit = 0
    N = int(input())
    tmp = N
    number = N
    if N == 0:
        break
    while N > 0:
        count_digit += N % 10
        N = N // 10
    count_digit2 = 0
    for p in range(11, 100000):
        tmp *= p
        number *= p
        while number > 0:
            count_digit2 += number % 10
            number = number // 10
        tmp = tmp // p
        number = tmp
        if count_digit == count_digit2:
            print(p)
            break
        count_digit2 = 0