fun main(args: Array<String>) {
    val n = readLine()!!.toInt()
    val v = readLine()!!.split(" ").map { it.toDouble() }

    val s = v.sorted()

    var value = s[0]
    for (i in 1 until v.size) {
        value = (value + s[i]) / 2.0
    }
    println(value)
}