mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    N = int(input())

    if N == 1:
        print(2)
        exit()
    elif N == 2:
        print(3)
        exit()

    for i in range(2, N+1):
        A = set()
        x = N
        cnt = 0
        while x:
            A.add(x % i)
            x //= i
            cnt += 1
        if cnt <= 2:
            break
        if len(A) == 1:
            print(i)
            exit()
    ans = N - 1
    for d in range(2, N+1):
        p = N // d - 1
        if p <= d:
            break
        if N % d == 0:
            ans = p
    print(ans)


if __name__ == '__main__':
    main()