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())
yaku = []
for i in range(2,2*10**6):
    if check(i):
        print(i)
        break
    if n%i == 0: yaku.append(n//i)
else:
    for i in yaku:
        p = n//i - 1
        if p*p > n: 
            print(p)
            break