
import java.util.Scanner

object Main {

  def read(): (Int, IndexedSeq[Int]) = {
    val sc: Scanner = new Scanner(System.in)
    val n = sc.nextInt
    val arr = (1 to n).map { _ =>
      sc.nextInt
    }
    sc.close()
    (n, arr)
  }


  def solve(n: Int, arr: IndexedSeq[Int]): Double = {
    val sorted = arr.sorted
    sorted.foldLeft(sorted.head: Double) { (stock, item) =>
      (stock + item) / 2
    }
  }


  def main(args: Array[String]): Unit = {
    val (a, s) = read()
    println(solve(a, s))
  }

}
