import scala.io.StdIn

object Main extends App {
  val n  = StdIn.readLine().toInt
  val v :Array[Double] = StdIn.readLine().split(" ").map(_.toDouble)

  print(v.sorted.tail.foldLeft(v.sorted.head) { (acc, elem) =>
    (acc + elem) / 2
  })

}
