import java.util.*

fun main(args: Array<String>) {
    val scanner = Scanner(System.`in`)
    val n = scanner.nextInt()
    val v = LongArray(n) { scanner.nextLong() }

    val ret = v.sorted()
        .map { it.toDouble() }
        .reduce { acc, l -> (acc + l) / 2.0 }
    println(ret)
}