require 'prime'

L, H = gets.split.map(&:to_i)

primes = Prime.each(Math.sqrt(H)).to_a.reverse

primes.each do |x|
  y = H / x
  n = y * x

  while n >= L
    if n.prime_division[0][0] >= x
      puts n
      exit
    end

    n -= x
  end
end