def Eratosthenes(N): #N以下の素数のリストを返す
    N+=1
    is_prime_list = [True]*N
    m = int(N**0.5)+1
    for i in range(3,m,2):
        if is_prime_list[i]:
            is_prime_list[i*i::2*i]=[False]*((N-i*i-1)//(2*i)+1)
    return [2] + [i for i in range(3,N,2) if is_prime_list[i]]

L,R = map(int,input().split())
primes = Eratosthenes(int(R**0.5)+100)
l = len(primes)
for p in primes[::-1]:
    if L <= p*p <= R:
        for q in primes[::-1]:
            if L <= p*q <= R:
                print(p*q)
                exit()

min_factor = [0]*(R-L+1)
for p in primes[::-1]:
    sind = (L+p-1)//p #gind = R//p
    for i in range(sind*p-L,R-L+1,p):
        min_factor[i] = p
    if L <= p <= R:
        min_factor[p-L] = 0
ans = val = 0
for i in range(R-L+1):
    if val <= min_factor[i]:
        ans = i
        val = min_factor[i]
print(ans+L)