object Main extends App {
  val scan = new java.util.Scanner(System.in)
  val numbers = Array.fill(25000)(true)
  for ( i <- 2 until 25000 )
    for ( l <- 2 until 25000; if i*l < 25000 )
      numbers(i*l) = false
  val primes = (0 to 25000).zip(numbers).filter(_._2).map(_._1).drop(2).toList
  val n = scan.next().toInt

  var memo = Array.fill(1+primes.length, 20000)(-1)
  memo(0)(0) = 0
  for ( (i, n) <- (1 to primes.length).zip(primes) ) {
    for ( l <- 0 until 20000 ) {
      memo(i)(l) = math.max(memo(i-1)(l), memo(i)(l))
      if (memo(i-1)(l) != -1 && l+n < 20000) {
        memo(i)(l+n) = math.max(memo(i-1)(l)+1, memo(i)(l+n))
        if (l+n==4) println("prime: " ++ n.toString)
      }
    }
  }

  println(memo(primes.length)(n))
}