package main

import (
	"fmt"
	"sort"
)

func main() {
	var n int
	fmt.Scan(&n)

	var arr []int

	for i := 0; i < n; i++ {
		var x int
		fmt.Scan(&x)
		arr = append(arr, x)
	}
	sort.Slice(arr, func(i, j int) bool { return arr[i] < arr[j]})

	var ans float64 = float64(arr[0])
	for i := 1; i < n ; i++ {
		ans = (ans + float64(arr[i])) / 2
	}

	fmt.Println(ans)

}
