require 'prime'

def main
  k = gets.to_i
  n = gets.to_i
  primes = Prime.take_while { |p| p <= n }.select { |p| k <= p }
  prime_hashes = primes.map { |p| [p, p % 9] }
  # prime_hashが入る
  queue = []
  max_length = 0
  max_head = nil

  prime_hashes.each do |item|
    index_of_item_val = queue.index { |_item| _item[1] == item[1] }
    queue = queue[(index_of_item_val + 1)..-1] if index_of_item_val
    queue << item
    if max_length <= queue.size
      max_head = queue[0][0]
      max_length = queue.size
    end
  end
  max_head
end

puts main