import java.util.Scanner;

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

        double strawberryPricePerKilo = Double.parseDouble(scanner.nextLine());
        double bananaKg = Double.parseDouble(scanner.nextLine());
        double orangeKg = Double.parseDouble(scanner.nextLine());
        double raspberryKg = Double.parseDouble(scanner.nextLine());
        double strawberryKg = Double.parseDouble(scanner.nextLine());

        double raspberryPrice = strawberryPricePerKilo - (strawberryPricePerKilo * 0.5);
        double orangePrice = raspberryPrice - (raspberryPrice * 0.4);
        double bananaPrice = raspberryPrice - (raspberryPrice * 0.8);

        double finalPrice = strawberryKg * strawberryPricePerKilo + bananaKg * bananaPrice
                + orangeKg * orangePrice + raspberryKg * raspberryPrice;

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