package c01_Simple_Calculations;

import java.util.Scanner;

public class p08_TriangleArea {

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

        int l = Integer.parseInt(scan.nextLine());
        int w = Integer.parseInt(scan.nextLine());
        int h = Integer.parseInt(scan.nextLine());
        double percentage = Double.parseDouble(scan.nextLine());

        double volume = l * w * h;
        volume *= 0.001;
        volume  -= volume * (percentage / 100);

        System.out.printf("%.3f", volume);
    }
}