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

public class Yuki275
{
	public static void Main()
	{
		var n = int.Parse(Console.ReadLine());
		var a = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).OrderBy(y => y).ToList();
		Console.WriteLine(n % 2 != 0 ? a[n / 2] : (a[n / 2] + a[n / 2 - 1]) / 2.0);
	}
}