import java.util.Scanner

import scala.collection.mutable.ListBuffer

object PrimeInt {
  val ps: Stream[Int] = 2 #:: Stream.from(3).filter(i => ps.takeWhile(j => j * j <= i).forall(k => i % k > 0))

  def isPrime(n: Int): Boolean = ps.takeWhile(_ <= n).contains(n)
}

object Primes extends Iterable[Long] {
  var checked = 2L
  val xs = ListBuffer(2L)

  def contains(i: Long): Boolean = xs.takeWhile(_ <= i).contains(i)

  def apply(i: Int): Long = {
    while (xs.length <= i) {
      var n = checked + 1
      while (xs.takeWhile(j => j * j <= n).exists(n % _ == 0)) {
        n += 1
      }
      xs.append(n)
      checked = n
    }
    xs(i)
  }

  override def iterator: Iterator[Long] = new Iterator[Long] {
    var i = 0

    override def hasNext: Boolean = true

    override def next(): Long = {
      val x = apply(i); i += 1; x
    }
  }
}

object Main {
  def main(args: Array[String]) {
    val result = solve(new Scanner(System.in))
    if (result.length > 0) println(result)
  }

  def solve(in: String): String = solve(new Scanner(in))

  def prime(n: Int, primes: Seq[Int]) = primes.forall(p => n % p != 0)

  def solve(sc: Scanner): String = {
    val X = sc.nextInt

    var i = X
    while (!PrimeInt.isPrime(i)) i += 1

    i.toString
  }
}
