object Q211 {
  def main(args: Array[String]): Unit = {
    val k = io.StdIn.readLine().toInt

    val primes = Seq(2, 3, 5, 7, 11, 13)
    val composites = Seq(4, 6, 8, 9, 10, 12)
    val numer = (for (prime <- primes; composite <- composites) yield prime * composite).count(_ == k)
    println(numer.toDouble / 36)
  }
}