from collections import defaultdict

def seachPrimeNum(N):
    max = int(N**0.5)
    seachList = [i for i in range(2,N+1)]
    primeNum = []
    while seachList[0] <= max:
        primeNum.append(seachList[0])
        tmp = seachList[0]
        seachList = [i for i in seachList if i % tmp != 0]
    primeNum.extend(seachList)
    return primeNum

def factorization(x):
    dic = defaultdict(int)
    for p in PL:
        if x in PL:
            dic[x] += 1
            return dic
        while x % p == 0:
            dic[p] += 1
            x //= p
        if x == 1:
            return dic

N, K = map(int,input().split())
PL = seachPrimeNum(N)
PL = set(PL)
F1s = factorization(N)
ans = 1
maxdiv = 1
for i in range(2,N):
    Fs = factorization(i)
    ndiv = 1
    for v in Fs.values():
        ndiv *= (v + 1)
    cnt = 0
    for k,v in F1s.items():
        cnt += min(Fs[k],v)
    if cnt < K:
        continue
    if ndiv > maxdiv:
        ans = i
        maxdiv = ndiv
print(ans)