import scala.annotation.tailrec
import scala.io.StdIn

object Problem006 {

  def primesIn(min: Int, max: Int) = {
    val sq = Math.sqrt(max).toInt

    @tailrec
    def sieve(xs: Seq[Int], result: Seq[Int]): Seq[Int] = {
      if (xs.isEmpty || xs.head > sq) {
        (xs.reverse ++ result).reverse
      } else {
        sieve(xs.tail.filter(_ % xs.head != 0), xs.head +: result)
      }
    }
    sieve((2 to max).toSeq, Seq()).filter(_ >= min)
  }

  def hash(n: Int): Int = {
    @tailrec
    def rec(i: Int, result: Int): Int = {
      if (i == 0 && result >= 10) rec(result, 0)
      else if (i == 0) result
      else rec(i / 10, result + i % 10)
    }
    rec(n, 0)
  }

  def searchMax(primes: Seq[Int], hashes: Seq[Int]): Int = {
    @tailrec
    def rec(start: Int, end: Int, maxStart: Int, maxLen: Int): Int = {
      if (end > primes.length) return maxStart

      val range = hashes.slice(start, end)
      if (range.size == range.distinct.size) {
        if (maxLen <= end - start) {
          rec(start, end + 1, primes(start), end - start)
        } else {
          rec(start, end + 1, maxStart, maxLen)
        }
      } else {
        rec(start + 1, end, maxStart, maxLen)
      }
    }

    rec(0, 1, 0, 0)
  }

  def proc(min: Int, max: Int): Int = {
    val primes = primesIn(min, max)
    val hashes = primes.map(hash)
    searchMax(primes, hashes)
  }

  def main(args: Array[String]) = {
    val k = StdIn.readInt()
    val n = StdIn.readInt()

    val result = proc(k, n)
    println(result)
  }
}