from math import gcd

def factors(n):
    f = []
    c = 0
    while n % 2 == 0:
        n //= 2
        c += 1
    if c > 0:
        f.append([2, c])
    p = 3
    while p * p <= n:
        if n % p == 0:
            c = 0
            while n % p == 0:
                n //= p
                c += 1
            if c > 0:
                f.append([p, c])
        p += 2
    if n != 1:
        f.append([n, 1])
    return f

def divisors(n):
    divs = []
    for d in range(1, int(n**0.5) + 1):
        if n % d == 0:
            divs.append(d)
            q = n // d
            if q != d:
                divs.append(q)
    return divs

N, K = map(int, input().split())

ans = 0
max_ndivs = 0
for i in range(2, N):
    g = gcd(i, N)
    k = sum(f[1] for f in factors(g))
    if k < K: continue
    ndivs = len(divisors(i))
    if ndivs > max_ndivs:
        max_ndivs = ndivs
        ans = i

print(ans)