fun main(args: Array<String>) {
  val count = readLine()!!.toInt()
  val list = readLine()!!.split(" ").map { it.toInt() }.toMutableList()
  list.sort()
  var ans: Float = ((list[0] + list[1]) / 2).toFloat()
  if(count > 2){
    for(i in 2..list.size-1) {
        ans = (ans + list[i]) / 2
    }
  }
  println(ans)
}