def factorize(n):
    factors = []
    
    for div in range(2, int(n**0.5)+1):
        cnt = 0
        
        while n % div == 0:
            n //= div
            cnt += 1
        
        if cnt > 0:
            factors.append((div, cnt))
    
    if n > 1:
        factors.append((n, 1))
    
    return factors
    
def gcd(a, b):
    while b:
        a, b = b, a % b
    return a
    
N, K = map(int, input().split())
prev_i_cnt = 0

for i in range(2, N):
    G = gcd(i, N)
    G_factors = factorize(G)
    
    if sum([G_factors_i[1] for G_factors_i in G_factors]) >= K:
        i_factors = factorize(i)
        i_cnt = 1
        
        for _, c in i_factors:
            i_cnt *= (c + 1)
    
        if i_cnt > prev_i_cnt:
            ans = i
            prev_i_cnt = i_cnt

print(ans)