import sys
import pypyjit
import itertools
import heapq
import math
from collections import deque, defaultdict
import bisect

input = sys.stdin.readline
sys.setrecursionlimit(10 ** 6)
pypyjit.set_param('max_unroll_recursion=-1')


def index_lt(a, x):
    'return largest index s.t. A[i] < x or -1 if it does not exist'
    return bisect.bisect_left(a, x) - 1


def index_le(a, x):
    'return largest index s.t. A[i] <= x or -1 if it does not exist'
    return bisect.bisect_right(a, x) - 1


def index_gt(a, x):
    'return smallest index s.t. A[i] > x or len(a) if it does not exist'
    return bisect.bisect_right(a, x)


def index_ge(a, x):
    'return smallest index s.t. A[i] >= x or len(a) if it does not exist'
    return bisect.bisect_left(a, x)


class Osa_k:
    # N以下の整数を素因数分解 O(NlogN)
    def __init__(self, N):
        self.min_factor = [i for i in range(N + 1)]
        for i in range(2, N + 1):
            if i * i > N:
                break
            if self.min_factor[i] == i:
                for j in range(2, N + 1):
                    if i * j > N:
                        break
                    if self.min_factor[i * j] > i:
                        self.min_factor[i * j] = i

    def factors(self, n):
        d = defaultdict(int)
        while n > 1:
            d[self.min_factor[n]] += 1
            n //= self.min_factor[n]
        return d


N, K = map(int, input().split())
osa_k = Osa_k(N)
fn = osa_k.factors(N)
ma_divs = 0
for i in range(1, N):
    fi = osa_k.factors(i)
    cnt = 0
    for k in fn.keys():
        cnt += min(fn[k], fi[k])
    if cnt < K:
        continue
    n_divs = 1
    for v in fi.values():
        n_divs *= (v + 1)
    if n_divs > ma_divs:
        ma_divs = n_divs
        ans = i
print(ans)