def convert_base(num, to_base, from_base = 10):
    # first convert to decimal number
    if isinstance(num, str):
        n = int(num, from_base)
    else:
        n = int(num)
    alphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    if n < to_base:
        return alphabet[n]
    else:
        return convert_base(n // to_base, to_base) + alphabet[n % to_base]

def IsPrime(n):
   d = 2
   while d * d <= n and n % d != 0:
       d += 1
   return d * d > n

a = int(input())
max_base = 2
min_count_of_zeros = 0

for i in range(2,32):
    if IsPrime(i):
        d = convert_base(a,i)
        count_of_zeros = d.count("0")
        if count_of_zeros > min_count_of_zeros:
            max_base = i
            min_count_of_zeros = count_of_zeros
print(max_base)