from math import gcd

n, k = map(int, input().split())

F = [[] for _ in range(n)]
for i in range(1, n):
    j = 1
    while j * j <= i:
        if i % j != 0:
            j += 1
            continue
        F[i].append(j)
        if j * j != i:
            F[i].append(i // j)
        j += 1

N = [1 for _ in range(n)]
N[1] = 0
i = 2
while i * i < n:
    if N[i] != 1:
        i += 1
        continue
    for j in range(i * 2, n, i):
        N[j] = N[i] + N[j // i]
    i += 1

max_, ans = 0, 0
for i in range(1, n):
    if N[gcd(i, n)] >= k and len(F[i]) > max_:
        ans = i
        max_ = len(F[i])
print(ans)