# x以下の素数の列挙,素因数分解,約数の列挙

x=10**6
    
import math 
L=math.floor(math.sqrt(x)) # 平方根を求める

Primelist=[i for i in range(x+1)]
Primelist[1]=0 # 1は素数でないので0にする.
 
for i in Primelist:
    if i>L:
        break
    if i==0:
        continue
    for j in range(2*i,x+1,i):
        Primelist[j]=0

Primes=[Primelist[j] for j in range(x+1) if Primelist[j]!=0]

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

if L==H:
    print(H)

elif H-L<=100:
    ANS=[]
    MAX=0

    for i in range(L,H+1):
        for p in Primes:
            if i!=p and i%p==0:
                if MAX<=p:
                    MAX=p
                    ANS=i
                break

    print(ANS)

else:
    r=H**(1/2)

    for i in range(len(Primes)):
        if Primes[i]>=r:
            ind=i
            break

    ANS=0
    MAX=0

    for i in range(ind,-1,-1):
        flag=0
        for j in range(i,len(Primes)):
            x=Primes[i]
            y=Primes[j]

            if x*y>H:
                break

            if L<=x*y<=H:
                flag=1
                ANS=x*y
                MAX=x

        if flag:
            break

    print(ANS)