from collections import Counter
from math import gcd
from functools import lru_cache


def prime_sieve(N):
    #sieve[i] : iの最小の素因数
    sieve = [0] * (N + 1)
    prime = []
    for i in range(2, N + 1):
        if sieve[i] == 0:
            sieve[i] = i
            prime.append(i)
        for p in prime:
            if p > sieve[i] or i * p > N:
                break
            sieve[i * p] = p
    return sieve


@lru_cache(maxsize=None)
def get_factor(N):
    cnt = 0
    while sieve[N]:
        cnt += 1
        N //= sieve[N]
    return cnt


def count_divisor(N):
    pf = []
    while sieve[N]:
        pf.append(sieve[N])
        N //= sieve[N]
    res = 1
    for v in Counter(pf).values():
        res *= v+1
    return res


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

ans = 0
div = 0
for x in reversed(range(1, N)):
    g = gcd(x, N)
    if get_factor(g) >= K:
        cnt = count_divisor(x)
        if cnt >= div:
            div = cnt
            ans = x

print(ans)