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

class Program
{
    static void Main(string[] args)
    {
        int[] point = Console.ReadLine().Split().Select(int.Parse).ToArray();
        Array.Sort(point);

        string ans = String.Format("{0:0.00}", (float)((point.Sum() - point[0] - point[5]) / 4.00));

        Console.WriteLine(ans);
        Console.Read();
    }
}