using System;

namespace AlcoholMarket
{
    class Program
    {
        static void Main(string[] args)
        {
            double whiskeyPrice = double.Parse(Console.ReadLine());
            double beerCount = double.Parse(Console.ReadLine());
            double wineCount = double.Parse(Console.ReadLine());
            double rakiaCount = double.Parse(Console.ReadLine());
            double whiskeyCount = double.Parse(Console.ReadLine());
            double rakiaPrice = whiskeyPrice / 2;
            double winePrice = rakiaPrice * 0.6;
            double beerPrice = rakiaPrice * 0.2;
            double moneyNeeded = beerCount * beerPrice + wineCount * winePrice + rakiaCount * rakiaPrice + whiskeyCount * whiskeyPrice;
            Console.WriteLine($"{moneyNeeded:f2}");


        }
    }
}