3 -> вариант 1

using System;

namespace _03
{
    class Program
    {
        static void Main(string[] args)
        {
            double width = double.Parse(Console.ReadLine());
            double length = double.Parse(Console.ReadLine());
            int countCameras = int.Parse(Console.ReadLine());
            string firmName = Console.ReadLine();

            double area = width * length;
            double price = 0;
            switch(firmName)
            {
                case "Dogramichka4You":
                    if (countCameras == 3)
                    {
                        price = 12;
                    }
                    else if (countCameras == 4)
                    {
                        price = 15;
                    }
                    else if (countCameras == 5)
                    {
                        price = 20;
                    }
                    break;
                case "TihoToplo":
                    if (countCameras == 3)
                    {
                        price = 15;
                    }
                    else if (countCameras == 4)
                    {
                        price = 14;
                    }
                    else if (countCameras == 5)
                    {
                        price = 18;
                    }
                    break;
                case "ChukChuk":
                    if (countCameras == 3)
                    {
                        price = 14;
                    }
                    else if (countCameras == 4)
                    {
                        price = 20;
                    }
                    else if (countCameras == 5)
                    {
                        price = 22;
                    }
                    break;
            }

            double totalPrice = area * price;
            Console.WriteLine($"Goshko has to spend {totalPrice:F2} leva.");


        }
    }
}