def check(i):
    x = n
    y = -1
    while x:
        q,r = x//i,x%i
        if y != -1 and y != r:
            return False
        y = r
        x //= i
    return True

n = int(input())
for i in range(2,n):
    if check(i):
        print(i)
        break
    if i*i > n:
        print(n-1)
        break