using System;

namespace _06.Fishland
{
    class Program
    {
        static void Main(string[] args)
        {
            double priceMackerel = double.Parse(Console.ReadLine());            //скумрия 6.9
            double priceSprat = double.Parse(Console.ReadLine());               // цаца 4.20
            double quantityBeltedBonito = double.Parse(Console.ReadLine());     //паламуд 1.5
            double quantityScad = double.Parse(Console.ReadLine());             //сафрид 2.5
            int quantityMussel = int.Parse(Console.ReadLine());                 //миди 1

            double priceBeltedbonito = priceMackerel * 1.60;
            double priceScad = priceSprat * 1.80;
            double priceMussel = 7.50;

            double total = quantityBeltedBonito * priceBeltedbonito + quantityScad * priceScad + quantityMussel * priceMussel;

            Console.WriteLine(Math.Round(total,2));

        }
    }
}