using System;
using System.Collections.Generic;

    class Program
    {
        static void Main(string[] args)
        {
            int N = int.Parse(Console.ReadLine());
            
            List<string> input = new List<string>();
            List<double> iList=new List<double>();
            int count=0;
            input.AddRange(Console.ReadLine().Split(' '));
            double answer =0;

            foreach(var s in input)
            {
                iList.Add(double.Parse(s));
            }
            iList.Sort();
            count=iList.Count;
            
            while(iList.Count!=1)
            {
                answer = (iList[0]+iList[1])/2;
                iList.RemoveAt(0);
                iList.RemoveAt(0);
                iList.Insert(0,answer);
            }

                Console.WriteLine(iList[0]);
        }
    }

