import scala.math._

object Main {
  def isPrime(n: Int): Boolean = {
    if (n <= 1) return false
    if (n == 2) return true
    if (n % 2 == 0) return false

    var p = 3
    while (p*p <= n) {
      if (n % p == 0) return false
      p += 2
    }
    return true
  }

  def main(args: Array[String]) {
    val sc = new java.util.Scanner(System.in)
    val n = sc.nextInt

    val ans = (max(4, n-100) to n+100).filter(!isPrime(_)).head
    println(ans)
  }
}