from math import gcd

def prime_factor(n):
    ass = []
    for i in range(2,int(n**0.5)+1):
        while n % i==0:
            ass.append(i)
            n = n//i
    if n != 1:
        ass.append(n)
    return len(ass)

def divisor(n):
    ass = []
    for i in range(1,int(n**0.5)+1):
        if n%i == 0:
            ass.append(i)
            if i**2 == n:
                continue
            ass.append(n//i)
    return len(ass)

def main():
    N, K = map(int, input().split())
    cnt = 0
    ans = 0
    for i in range(1, N):
        max_div = gcd(i, N)
        if prime_factor(max_div) >= K:
            d = divisor(i)
            if cnt < d:
                cnt = d
                ans = i

    print(ans)



if __name__ == "__main__":
    main()