using System;

public class Program

{

    public static void Main()

    {

        double berryPrice = double.Parse(Console.ReadLine());

        double banana = double.Parse(Console.ReadLine()); 

        double orange = double.Parse(Console.ReadLine());

        double raspberries = double.Parse(Console.ReadLine());

        double berry = double.Parse(Console.ReadLine());

        double raspberriesPrice = berryPrice / 2;

        double sum = CalculateSum(berryPrice, berry) + CalculateSum(raspberriesPrice - (0.8 * raspberriesPrice), banana) + CalculateSum(raspberriesPrice - (0.4 * raspberriesPrice), orange) + CalculateSum(raspberriesPrice, raspberries);

        Console.WriteLine(sum.ToString("N2"));

    }

    private static double CalculateSum(double price, double quantity) {

        return price * quantity;

    }

}