def solve():
    n = int(input())
    for p in range(2, 10 ** 6 + 1):
        acc = 1
        pk = 1
        while acc <= n:
            if n % acc == 0 and n // acc < p:
                return p
            pk *= p
            acc += pk
    p = n - 1
    i = 2
    while i * i <= p:
        if p % i == 0:
            return n + 1    
        i += 1
    return p

print(solve())