using System;

public class Program

{

    public static void Main()

    {

        int bas, ad, floor, price=0;

        Console.WriteLine("enter base price");

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

        Console.WriteLine("enter add price");

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

        Console.WriteLine("enter floor number");

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

        if(floor==0)

        {

            price=bas+1000;

        }

        else if(floor>=1 && floor<=5)           

        {

            price=bas+(floor*ad);

            if(floor==1)

                price=price-4000;

        }

        else

            price=3*bas;

        Console.Write("the cost is: "+price);

    }

}