using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace C
{
    class Program
    {
        static void Main(string[] args)
        {
            var N = int.Parse(Console.ReadLine());
            var v = Console.ReadLine().Split(' ').Select(item => double.Parse(item)).OrderBy(item => item).ToList();
            var q = new Queue<double>(v);
            while (q.Count > 1)
            {
                var a = q.Dequeue();
                var b = q.Dequeue();
                q.Enqueue((a + b) / 2);
;           }
            Console.WriteLine(q.Dequeue());
        }
    }
}
