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

namespace atcoder_csharp
{
    class Program
    {
        static void Main(string[] args)
        {
            var n = Util.ReadInt();
            var values = Util.ReadInts().OrderBy(v => v).ToList();
            var avg = values[0];
            for(var i = 1; i < n; i++) {
                avg = (values[i] + avg)/2;
            }
            Console.WriteLine(avg);
        }
  
    }

    class Util {
        private const bool debug = false;

        public static string ReadStr() {
            return debug ? ReadDebugLine() : Console.ReadLine();
        }

        public static List<string> ReadStrs() {
            return ReadStr().Split(' ').ToList();
        }

        public static int ReadInt() {
            return int.Parse(ReadStr());
        }     

        public static List<int> ReadInts() {
            return ReadStrs().Select(s => int.Parse(s)).ToList();
        } 

        private static List<string> _lines;
        private static int _lineIndex = 0;
        private static string ReadDebugLine() {
            if(_lines == null) {
                _lines = System.IO.File.ReadAllLines("debug.txt").ToList();
            }
            return _lines[_lineIndex++];
        }

    }
}
