using System;

public class Program

{

    public static void Main()

    {

        double buget = double.Parse(Console.ReadLine());

        int nights = int.Parse(Console.ReadLine());

        double nightsPrice = double.Parse(Console.ReadLine());

        double more = double.Parse(Console.ReadLine());

        double procentMore = more /100;

        //Console.WriteLine(procentMore);

        if (nights>7)

        {

            nightsPrice = nightsPrice - (nightsPrice* 0.05);

        }

        double allNight = nights * nightsPrice;

        double allBuget =allNight + (buget * procentMore);

            double finalPrice = buget - allBuget;

        if (finalPrice<0)

        {

            finalPrice = finalPrice *(-1);

            Console.WriteLine("{0:F2} leva needed" , finalPrice);

        }

            else 

                Console.WriteLine("Ivanovi will be left with {0:F2} leva after vacation." , finalPrice);

    }

}