import java.util.Scanner;

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

        int speed      = Integer.parseInt(scanner.nextLine());
        int firstTime  = Integer.parseInt(scanner.nextLine());
        int secondTime = Integer.parseInt(scanner.nextLine());
        int thirdTime  = Integer.parseInt(scanner.nextLine());

        double firstTimeInHours  = firstTime / 60.0;
        double secondTimeInHours = secondTime / 60.0;
        double thirdTimeInHours  = thirdTime / 60.0;
        double distanceWithFirstSpeed                 = speed * firstTimeInHours;
        double speedAfterAcceleration                 = speed  + (0.10 * speed);
        double distanceAfterAcceleationWithSecondTime = speedAfterAcceleration * secondTimeInHours;
        double speedAfterSlowDown                     = speedAfterAcceleration - (0.05 * speedAfterAcceleration);
        double distanceAfterSlowDownWithThirdTime     = speedAfterSlowDown * thirdTimeInHours;
        double total = distanceWithFirstSpeed
                     + distanceAfterAcceleationWithSecondTime
                     + distanceAfterSlowDownWithThirdTime;
        System.out.printf("%.2f", total);
    }
}