# N<10**5なので全探索可能

from collections import defaultdict

# 辞書型に改造
def factorization(n):
    arr = defaultdict(int)
    temp = n
    for i in range(2, int(-(-n**0.5//1))+1):
        if temp%i==0:
            cnt=0
            while temp%i==0:
                cnt+=1
                temp //= i
            arr[i] = cnt
    if temp!=1:
        arr[temp] = 1
    if arr==[]:
        arr[n] = 1
    return arr

#factorization(7)

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

mx_count = 0
candidates = []
for n in range(1, N):
    common = 0
    factors = factorization(n)
    count = 1
    for p in factors:
        common += min(N_factors[p], factors[p])
        count *= (factors[p]+1)
    #print('n', n, 'common', common, 'count', count)
    if common >= K:
        if count > mx_count:
            mx_count = count
            candidates = []
            candidates.append(n)
        elif count == mx_count:
            candidates.append(n)
ans = min(candidates)
print(ans)