import math
def getPrime():
	primes = [2]
	for i in range(3,100000 + 1):
		f = True
		j = 2
		while j * j <= i:
			if i % j == 0:
				f = False
				break
			j += 1
		if f:
			primes.append(i)
	return primes
L,H = map(int,input().split())
prime = getPrime()
prime = sorted(prime,reverse=True)
find = False
for i in range(len(prime)):
	if prime[i] * prime[i] <= H:
		j = H // prime[i] * prime[i]
		while j >= max(L,prime[i] * prime[i]):
			k = len(prime) - 1
			while k > i:
				if j % prime[k] == 0:break
				k -= 1
			if k == i:
				print(j)
				find = True
				break
			j -= prime[i]
		if find:break
	if find:break