import math

def is_prime(n):
    if n == 2:
        return True
    return pow(2, n-1, n) == 1

def min_prime(n, prime_list):
    for p in prime_list:
        if n % p == 0:
            return p
    return n

L, H = map(int, input().split())

prime_list = [i for i in range(2, (int)(math.sqrt(H)) + 1) if is_prime(i)]

H_half = math.floor(H / 2) + 1

for p in reversed(prime_list):
    for i in reversed(range(p, math.floor(H / p) + 1)):
        if L <= i * p <= H:
            if min_prime(i, prime_list) >= p:
                print(i * p)
                exit(0)
        else:
            break