import java.util.*

fun main(args: Array<String>) {
  val sc = Scanner(System.`in`)
  val n = sc.nextInt()
  val v = (1..n).map { sc.nextInt()}

  println(abc138c(n, v))
}

private fun abc138c(n: Int, v: List<Int>): Double {
  val sorted = v.sorted().map { it.toDouble() }

  var pre = sorted.get(0).toDouble()
  for (i in 1 until n) {
    pre = sorted.get(i).toDouble() + pre
    pre /= 2.0
  }

  return pre
}
