Computer Store

using System;

namespace MidExamComputerStoreExercise1
{
    class Program
    {
        static void Main(string[] args)
        {
            string command = Console.ReadLine();
            double priceWithoutTax = 0;
            while(command != "regular" && command != "special")
            {

                double price = double.Parse(command);
                if (price < 0)
                {
                    Console.WriteLine("Invalid price!");
                    command = Console.ReadLine();
                    continue;
                }
                priceWithoutTax += price;
                command = Console.ReadLine();
            }
            if (priceWithoutTax == 0)
            {
                Console.WriteLine("Invalid order!");
                return;
            }

            double taxes = 0.20 * priceWithoutTax;
            double allPrice = priceWithoutTax + taxes;
            if(command == "special")
            {
                allPrice = allPrice - allPrice* 0.10;
            }
            Console.WriteLine($"Congratulations you've just bought a new computer!\nPrice without taxes: {priceWithoutTax:F2}$\nTaxes: {taxes:F2}$\n-----------\nTotal price: {allPrice:F2}$");
        }
    }
}