using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;

public class Program
{
    static List<double> results = new List<double>();

    public static void Main(string[] args)
    {
        var n = int.Parse(Console.ReadLine());
        var valuesStr = Console.ReadLine().Split(' ');
        Array.Sort(valuesStr);
        List<double> values = new List<double>();
        double value = double.Parse(valuesStr[0]);

        for (int i = 1; i < valuesStr.Length; i++)
        {
            value = (value + double.Parse(valuesStr[i])) / 2.0;
        }
      
        Console.WriteLine(value);
    }
}