import java.util.Scanner

object Main extends App {
  val sc = new Scanner(System.in)

  val n = sc.nextInt
  val vs = Seq.fill(n)(sc.nextInt).sorted

  val res = vs.sorted.tail.foldLeft(vs.sorted.head.toDouble){case (tmp, acc) =>
    (tmp + acc) / 2
  }



  println(res)


}
