import java.util.Scanner;

public class Alcohol {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        double priceWiski = Double.parseDouble(scanner.nextLine());
        double beerLitters = Double.parseDouble(scanner.nextLine());
        double wineLitters = Double.parseDouble(scanner.nextLine());
        double rakiaLitters = Double.parseDouble(scanner.nextLine());
        double wiskiLitters = Double.parseDouble(scanner.nextLine());

        double priceRakia =priceWiski / 2;
        double winePrice = priceRakia*0.4;
        double beerPrice = priceRakia*0.8;

        double sumWiski = priceWiski*wiskiLitters;
        double sumBeer = beerPrice*beerLitters;
        double sumWine = winePrice*wineLitters;
        double sumRakia = priceRakia*rakiaLitters;



        double allSum = sumWiski + sumBeer + sumWine + sumRakia;

        System.out.printf("%.2f", allSum );
    }}