using System;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        var N = int.Parse(Console.ReadLine());
        var input = Console.ReadLine().Split(' ');
        var list = new List<int>();
        int midIdx;

        foreach (var d in input)
        {
            list.Add(int.Parse(d));
        }
        list.Sort();
        if (N % 2 == 0)
        {
            midIdx = N / 2;
            Console.WriteLine("{0:f1}", (list[midIdx - 1] + list[midIdx]) / 2.0);
        }
        else
        {
            midIdx = N / 2;
            Console.WriteLine("{0:f1}", list[midIdx]);
        }
     }
}