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

namespace YukiCoder
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.ReadLine();
            var pa = Console.ReadLine().Split().Select(int.Parse).OrderBy(n=>n).ToList();
            int cn = pa.Count;
            int m1 = pa[(cn - 1) / 2];
            int m2 = pa[cn / 2];

            Console.WriteLine((m1 + m2) / 2.0);
            Console.ReadLine();
        }
    }
}