package com.company;

import java.util.Scanner;

public class AddBags {

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

        double priceBagUp20Kg = Double.parseDouble(sc.nextLine());
        double bagKg = Double.parseDouble(sc.nextLine());
        int daysUntilTravel = Integer.parseInt(sc.nextLine());
        int bagCounter = Integer.parseInt(sc.nextLine());

        if (bagKg < 10) {
            priceBagUp20Kg = priceBagUp20Kg - (priceBagUp20Kg * 0.20);
        } else if (bagKg >= 10 || bagKg <= 20) {
            priceBagUp20Kg = priceBagUp20Kg - (priceBagUp20Kg * 0.50);
        } else if (bagKg > 20) {
            priceBagUp20Kg = Double.parseDouble(sc.nextLine());
        }

        if (daysUntilTravel > 30) {
            priceBagUp20Kg = priceBagUp20Kg + (priceBagUp20Kg * 0.10);
        } else if (daysUntilTravel >= 7 || daysUntilTravel <= 30) {
            priceBagUp20Kg = priceBagUp20Kg + (priceBagUp20Kg * 0.15);
        } else if (daysUntilTravel <= 7) {
            priceBagUp20Kg = priceBagUp20Kg + (priceBagUp20Kg * 0.40);
        }

        double totalSum = priceBagUp20Kg * bagCounter;

        System.out.printf("The total price of bags is: %.2f lv.", totalSum);
    }
}