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
    d = 1
    div_f, div_b = [], []
    while d * d <= n:
        if n % d == 0:
            div_f.append(d)
            div_b.append(n // d)
        d += 1
    divs = div_f
    divs += reversed(div_b)
    for d in reversed(divs):
        p = n // d - 1
        if d < p:
            return p
    return n + 1

print(solve())