#!/usr/bin/env python3

import math
import random


def find_min_factor(n):
    assert n > 0
    if n % 2 == 0:
        return 2
    for i in range(3, n, 2):
        if i * i > n:
            return n
        elif n % i == 0:
            return i


def is_prime_miller_rabin(n, k=30):
    assert n > 0
    if n == 2:
        return True
    elif n == 1 or n % 2 == 0:
        return False
    d = n - 1
    s = 0
    while d % 2 == 0:
        d //= 2
        s += 1
    for i in range(k):
        a = random.randint(1, n - 1)
        if pow(a, d, n) != 1:
            for r in range(0, s):
                if pow(a, d * 2 ** r, n) == n - 1:
                    break
            else:
                return False
    return True


def solve(l, h):
    answer = 0
    max_min_factor = 0
    # c = p * d
    #   c (>= 4) : a composite number
    #   p (>= 2) : a prime number
    #   d (>= 2) : an integer
    for p in range(2, math.floor(math.sqrt(h)) + 1)[:: -1]:
        if p < max_min_factor:
            break
        elif h // p * p < l or not is_prime_miller_rabin(p):
            continue
        for d in range(p, h // p + 1)[:: -1]:
            c = p * d
            if l > c:
                break
            f = find_min_factor(c)
            if max_min_factor < f or max_min_factor == f and answer < c:
                max_min_factor = f
                answer = c
    return answer


def main():
    l, h = map(int, input().split())
    print(solve(l, h))


if __name__ == '__main__':
    main()