fun main(args: Array<String>) {
    val n = readLine()!!.toInt()
    val v = readLine()!!.split(" ").map { it.toDouble() }.toMutableList()
    v.sort()
    var x = (v.first() + v[1]) / 2.0
    if (n > 2) {
        for (i in 2 until n) {
            x = (x + v[i]) / 2.0
        }
    }
    println(x)
}