import sys
input = sys.stdin.readline

N = int(input())
# 1
ans = N - 1
# 2
i = 2
while i * i <= N:
    if N % i == 0 and i < N // i - 1:
        ans = min(ans, N // i - 1)
    i += 1

# >= 3
p = 2
while p * p <= N:
    n = N
    s = set()
    while n > 0:
        s.add(n % p)
        n //= p
    if len(s) == 1:
        ans = min(ans, p)
    p += 1

print(ans)