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

namespace program {
  class Program {
    static void Main()
    {
      var n = Input.ScanInt();
      var a = Input.ScanDoubleArray();
      Array.Sort(a);
      
      Heap h = new Heap(a.ToList());
      
      double x,y;
      while(h.Count >1){
        x = h.Pop();
        y = h.Pop();
        h.Push((x+y)/2);
      }
      
      Out(h.Pop());
    }
    static public void Out(object s) { Console.Write($"{s} "); }
  }
  
  static class Input {
    static public int ScanInt() { return int.Parse(Console.ReadLine()); }
    static public uint ScanUint() { return uint.Parse(Console.ReadLine()); }
    static public double ScanDouble() { return double.Parse(Console.ReadLine()); }
    static public long ScanLong() { return long.Parse(Console.ReadLine()); }
    static public ulong ScanUlong() { return ulong.Parse(Console.ReadLine()); }
    static public int[] ScanIntArray() { return Console.ReadLine().Split().Select(x => int.Parse(x)).ToArray(); }
    static public uint[] ScanUintArray() { return Console.ReadLine().Split().Select(x => uint.Parse(x)).ToArray(); }
    static public double[] ScanDoubleArray() { return Console.ReadLine().Split().Select(x => double.Parse(x)).ToArray(); }
    static public long[] ScanLongArray() { return Console.ReadLine().Split().Select(x => long.Parse(x)).ToArray(); }
    static public ulong[] ScanUlongArray() { return Console.ReadLine().Split().Select(x => ulong.Parse(x)).ToArray(); }

    static public string ScanStr() { return Console.ReadLine(); }
    static public string[] ScanStrArray() { return ScanStr().Split(); }
  }
  
  static class MyMath {
    public static int GCD(int a, int b) {
        Func<int, int, int> gcd = null;
        gcd = (x, y) => y == 0 ? x : gcd(y, x % y);
        return a > b ? gcd(a, b) : gcd(b, a);
    }
    public static long GCD(long a, long b) {
        Func<long, long, long> gcd = null;
        gcd = (x, y) => y == 0 ? x : gcd(y, x % y);
        return a > b ? gcd(a, b) : gcd(b, a);
    }
    public static long extGCD(long a, long b, ref long x, ref long y) {
      if(b==0) {
        x=1; 
        y=0;
        return a;
      }
      var d = extGCD(b, a%b, ref y, ref x);
      y -= a/b *x;
      return d;
    }
    public static int LCM(int a, int b) { return a * b / GCD(a, b); }
    public static long LCM(long a, long b) { return a * b / GCD(a, b); }
  }
    public class Heap
    {
        List<double> array;
        Func<double, double, bool> Compare; // default: x < y ?
        private void swap(int a, int b)
        {
            double tmp = array[a];
            array[a] = array[b];
            array[b] = tmp;
        }
        public void Push(double element)
        {
            int n = array.Count;
            array.Add(element);
            
            while (n != 0)
            {
                int i = (n - 1) / 2;
                if (Compare(array[n], array[i]))
                    swap(i, n);
                n = i;
            }
        }
        public double Pop()
        {
            int n = array.Count - 1;
            double element = array[0];
            array[0] = array[n];
            array.RemoveAt(n);

            for (int i = 0, j; (j = 2 * i + 1) < n; i = j)
            {
                if ((j != n - 1) && Compare(array[j+1], array[j]))
                    j++;

                if (Compare(array[j], array[i]))
                    swap(i, j);
            }
            return element;
        }
      public int Count{get{return array.Count;}}

        public Heap() { array = new List<double>(); Compare = (x, y) => x < y; }
        public Heap(List<double> a) { array = a.ToList();  Compare = (x, y) => x < y;}
    }
}


Measured memory_bytes: 13524