using System;
using System.Linq;
using System.Collections.Generic;
public class Hello{
    public static void Main(){
        var N = int.Parse(Console.ReadLine());
        var a = Console.ReadLine().Split(' ').Select(double.Parse).ToList();
        a.Sort();
        var ans = a[0];
        
        for(var i = 1; i < N;i++){
            ans = (ans + a[i]) / 2;
        }
        Console.WriteLine(ans);
    }
}
