import java.util.*

fun main(args: Array<String>) {
    val scanner = Scanner(System.`in`)
    val n = scanner.nextInt()
    val array = Array(n, {0.0})
    for(i in 0..n-1){
        array[i] = scanner.nextDouble()
    }
    array.sortDescending()
    var result = array[1]
    for(i in 2..n-1){
        result = (result+array[i])/2
    }
    println((array[0]+result)/2)
}