L,R=map(int,input().split())
v=[0]*(10**7)
for x in range(2,10**7):
  if v[x]==1:
    continue
  for y in range(2,10**7):
    if x*y>=10**7:
      break
    v[x*y]=1
p=[]
for x in range(3,10**7):
  if v[x]==0:
    p.append(x)
from math import isqrt
for i in range(len(p)):
  a=p[i]
  if a**4>R:
    break
  for j in range(i+1,len(p)):
    b=p[j]
    if a*a*b*p[j+1]>R:
      break
    r=R//(a*a*b)
    l=(L+a*a*b-1)//(a*a*b)
    l=max(l,p[j+1])
    z=-1
    for x in range(l,r+1):
      ans=True
      K=isqrt(x)
      for y in range(2,K+1):
        if x%y==0:
          ans=False
          break
      if ans==True:
        z=x
        break
    if z>0:
      print(a*a*b*z)
      exit()