N = 200200
isprime = [True] * N
isprime[0] = isprime[1] = False
for i in range(2, int(N ** 0.5 + 1)):
    if not isprime[i]:
        continue
    for j in range(i * i, N, i):
        isprime[j] = False

k = int(input())
n = int(input())
primes = []
hashes = []
for i in range(k, n + 1):
    if isprime[i]:
        primes.append(i)
        hashes.append(i % 9)
max_ = 0
ans = 0
le = len(primes)
tf = [False] * 9
r = 0
for l in range(le):
    while r < le and not tf[hashes[r]]:
        tf[hashes[r]] = True
        r += 1
    if r - l >= max_:
        max_ = r - l
        ans = primes[l]
    tf[hashes[l]] = False
print(ans)