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

namespace yuki0715_A
{
    class Program
    {
        static void Main(string[] args)
        {
            var x = getsplit();
            var A = Array.ConvertAll(x, int.Parse);
            int max = -1;
            int min = 101;
            int maxm = -1;
            int minm = -1;
            for (int i = 0; i < A.Length; i++)
            {
                if (A[i]>max)
                {
                    max = A[i];
                    maxm = i;
                }
                if (A[i]<min)
                {
                    min = A[i];
                    minm = i;
                }
            }
            int sum = 0;
            for (int i = 0; i < A.Length; i++)
            {
                if (minm == maxm)
                {
                    sum = A[i] * 4;
                    break;
                }
                if (i!=minm && i!= maxm)
                {
                    sum += A[i];
                }
            }
            double ans = (double)sum / 4;
            Console.WriteLine(ans.ToString("f2"));
        }
        public static string[] getsplit()
        {
            string[] x = Console.ReadLine().Split(' ');
            return x;
        }
        public static int getint()
        {
            int x = int.Parse(Console.ReadLine());
            return x;
        }
    }
}