from math import gcd
#素因数列挙
def prime_factorize(n):
    a = []
    while n % 2 == 0:
        a.append(2)
        n //= 2
    f = 3
    while f * f <= n:
        if n % f == 0:
            a.append(f)
            n //= f
        else:
            f += 2
    if n != 1:
        a.append(n)
    return a

#約数列挙
def make_divisors(n):
    lower_divisors , upper_divisors = [], []
    i = 1
    while i*i <= n:
        if n % i == 0:
            lower_divisors.append(i)
            if i != n // i:
                upper_divisors.append(n//i)
        i += 1
    return lower_divisors + upper_divisors[::-1]

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

ans,count = 0,0
for i in range(N-1,0,-1):
  GCD = gcd(N,i)
  Pr_GCD = prime_factorize(GCD)
  if len(Pr_GCD) >= K:
    lenGcd = len(make_divisors(i))
    if lenGcd >= count:
      count = lenGcd
      ans = i
  
print(ans)