string input = Console.ReadLine().ToLower();
            double sum = 0;

            while (input != "start")
            {
                double coins = double.Parse(input);

                switch (coins)
                {
                    case 0.1:
                        sum += 0.1;
                        break;
                    case 0.2:
                        sum += 0.2;
                        break;
                    case 0.5:
                        sum += 0.5;
                        break;
                    case 1.0:
                        sum += 1.0;
                        break;
                    case 2.0:
                        sum += 2.0;
                        break;
                    default:
                        Console.WriteLine($"Cannot accept {coins}");
                        break;

                }

                input = Console.ReadLine().ToLower();

            }