package abc138.c

import scala.io.StdIn

object Main {

  def main(args: Array[String]): Unit = {

    val n = StdIn.readLine().toInt
    val vs = StdIn.readLine().split(' ').toVector.map(_.toDouble).sorted
    assert(!vs.isEmpty)
    val ans = vs.tail.foldLeft(vs.head)((acc, v) => (acc + v) / 2)
    println(ans)

  }

}
