using System;

namespace Dieta
{
    class Program
    {
        static void Main(string[] args)
        {
            double berriesPrice = double.Parse(Console.ReadLine());
            double bananasQuantity = double.Parse(Console.ReadLine());
            double orangesQuantity = double.Parse(Console.ReadLine());
            double raspberriesQuantity = double.Parse(Console.ReadLine());
            double berriesQuantity = double.Parse(Console.ReadLine());

            double raspberriesPrice = berriesPrice / 2;
            double orangesPrice = raspberriesPrice - (raspberriesPrice * 0.4);
            double bananasPrice = raspberriesPrice - (raspberriesPrice * 0.8);

            double berriessSum = berriesPrice * berriesQuantity;
            double bananasSum = bananasPrice * bananasQuantity;
            double orangesSum = orangesPrice * orangesQuantity;
            double rasperriesSum = raspberriesPrice * raspberriesQuantity;

            double moneyNeeded = bananasSum + berriessSum + orangesSum + rasperriesSum;

            Console.WriteLine($"{moneyNeeded:f2}");
        }
    }
}