import math
L,H=map(int,raw_input().split())

upperBound = 100001
isPrime=[True for i in range((upperBound-3)/2+1)]
for i in range((int(math.sqrt(upperBound-3))-3)/2+1): # k*k = (2i+3)^2 <= upperBound-3 
   if isPrime[i]:
      k = i+i+3 # this is prime number
      # false out non_prime number from k*k
      # k*k = 4i^2+12i+9 = 2*(2i^2+6i+3)+3
      # k*(k+1) = 2*(2i^2+6i+3)+3 + 2i+3 ... even number. skip
      # k*(k+2) = 2*(2i^2+6i+3+k)+3 
      non_prime = k*(i+1)+i
      for j in range(non_prime,(upperBound-3)/2+1,k):
         isPrime[j]=False
primes = [2] + [i+i+3 for i in range((upperBound-3)/2+1) if isPrime[i]==True]

primes.reverse()
for i,p in enumerate(primes):
    #print p
    if H/p < p:
        continue
    for c in range((H/p)*p, L-1, -p):
        if c==p:
            break
        ok = True
        for j in range(i+1,len(primes)):
            q=primes[j]
            if c%q==0:
                ok=False
                break
        if ok:
            print c
            exit()