import sys
L, R = map(int, input().split())
ans, maxP = 0, 0
sqrt = int(R**0.5)
N = sqrt + 10
isprime = [1] * N

for i in range(2, N):
    if isprime[i]:
        for b in range(i + i, N, i):
            isprime[b] = 0
primes = [p for p in range(2, N) if isprime[p]]
smaller = list(primes)

for p in reversed(primes):
    smaller.pop()
    for x in reversed(range(max(p * p, (L + p - 1) // p * p), R + 1, p)):
        if all(x % b != 0 for b in smaller):
            print(x)
            sys.exit()