import scala.collection.immutable.IndexedSeq
import scala.io.StdIn

object Problem012 {

  def primesIn(max: Int): IndexedSeq[Int] = {
    val checked = Array.fill(max + 1)(false)

    for {
      i <- 2 to max
      if !checked(i)
    } yield {
      (i to max by i) foreach {
        checked(_) = true
      }
      i
    }
  }

  def proc(n: Int, a: Seq[Int]): Int = {
    if (n == 10) return 5000000 - 1

    val primes = primesIn(5000000)
    val requiredChar: Set[Int] = a.map(_ + '0').toSet

    var result = -1
    var K = 1
    var usingChar: Set[Int] = Set.empty
    var inRange = false

    def outOfRange(p: Int): Boolean = inRange && !isValid(p)
    def isValid(p: Int): Boolean = (p.toString.map(_.toInt).toSet diff requiredChar).isEmpty

    primes foreach { p =>
      if (isValid(p)) {
        usingChar ++= p.toString.map(_.toInt).toSet
        inRange = true
      } else if (outOfRange(p)) {
        if (usingChar == requiredChar) {
          val L = p - 1
          result = result max (L - K)
        }
        usingChar = Set.empty
        inRange = false
        K = p + 1
      } else if (!isValid(p)) {
        K = p + 1
      }
    }

    result
  }

  def main(args: Array[String]) {
    val n = StdIn.readInt()
    val a = StdIn.readLine().split(" ").map(_.toInt)

    val result: Int = proc(n, a)
    println(result)
  }
}