import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import numpy as np

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

def make_prime(U):
    is_prime = np.zeros(U,np.bool)
    is_prime[2] = 1
    is_prime[3::2] = 1
    M = int(U**.5)+1
    for p in range(3,M,2):
        if is_prime[p]:
            is_prime[p*p::p+p] = 0
    return is_prime, is_prime.nonzero()[0]

_,primes = make_prime(N + 100)

primes = primes[(K <= primes) & (primes <= N)]

H = 1<<(primes % 9)

H = np.append(H,[1023] * 10)

Hset = [H]
for _ in range(10):
    Hset.append(Hset[-1][:-1] | Hset[-1][1:])

for i,H in enumerate(Hset,1):
    popcount = np.zeros_like(H)
    for j in range(20):
        popcount += (H >> j)&1
    is_ok = popcount[:len(primes)] == i
    if not np.any(is_ok):
        break
    answer = (primes * is_ok).max()

print(answer)