object Main {
  def main(args: Array[String]): Unit = {
    val sc = new java.util.Scanner(System.in)
    val n = sc.nextInt
    val u = List.fill(n)(BigDecimal(sc.nextInt)).sorted
    println(calc(u)(0))

    def calc(us: List[BigDecimal]): List[BigDecimal] = us.length == 1 match {
      case true => us
      case _ => {
        calc(us.take(2).sum / 2 :: us.drop(2))
      }
    }
  }
}