def primes2(limit):
    ''' returns a list of prime numbers upto limit.
    source: Rossetta code: Sieve of Eratosthenes
    http://rosettacode.org/wiki/Sieve_of_Eratosthenes#Odds-only_version_of_the_array_sieve_above
    '''
    if limit < 2: return []
    if limit < 3: return [2]
    lmtbf = (limit - 3) // 2
    buf = [True] * (lmtbf + 1)
    for i in range((int(limit ** 0.5) - 3) // 2 + 1):
        if buf[i]:
            p = i + i + 3
            s = p * (i + 1) + i
            buf[s::p] = [False] * ((lmtbf - s) // p + 1)
    return [2] + [i + i + 3 for i, v in enumerate(buf) if v]


def solve(L, H):
    maxp = int(H**0.5)
    ps = primes2(maxp)
    for p in ps[::-1]:
        pp = find_pseudo_prime(p, L, H, ps)
        if pp:
            return pp

def find_pseudo_prime(p, L, H, ps):
    lower = L//p + (1 if L%p else 0)
    for q in range(H//p, lower - 1, -1):
        for r in ps:
            if r >= p:
                return p * q
            if q % r == 0:
                break
    return 0

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