def factorization_num(n):
    arr = []
    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.append([i, cnt])

    if temp!=1:
        arr.append([temp, 1])

    cnt = 0
    for _, b in arr:
        cnt += b
    return cnt

def div(n):
    if n <= 0:
        return []
    S = set()
    i = 1
    while i * i <= n:
        if n % i == 0:
            S.add(i)
            S.add(n // i)
        i += 1
    return S

N, K = map(int, input().split())
ans = N
maxv = -1
for d in div(N):
    if factorization_num(d) < K:
        continue
    for v in range(d, N, d):
        S = div(v)
        if len(S) > maxv:
            ans = v
            maxv = len(S)
print(ans)