Конвертер валют

using System;
using System.Security.Policy;

internal class Program
{
    static void Main(string[] args)
    {
        const string CommandConvertRublesToDollars = "1";
        const string CommandConvertDollarsToRubles = "2";
        const string CommandConvertRublesToYuan = "3";
        const string CommandConvertYuanToRubles = "4";
        const string CommandConvertDollarsToYuan = "5";
        const string CommandConvertYuanToDollars = "6";
        const string CommandExit = "7";
        const string CommandShowMistake = "Ошибка";

        float rub = 100000;
        float yuan = 200;
        float dollars = 50;
        float exchangeRublesToDollars = 0.01078f;
        float exchangeDollarsToRubles = 92.71f;
        float exchangeRublesToYuan = 0.0757f;
        float exchangeYuanToRubles = 13.22f;
        float exchangeDollarsToYuan = 7.01f;
        float exchangeYuanToDollars = 0.1426f;
        float amountMoney = 0;
        string userInput;
        bool isWorkProgram = true;

        while (isWorkProgram)
        {
            Console.Clear();
            Console.WriteLine($"На балансе:\nРублей = {rub}\nЮаней = {yuan}\nДолларов = {dollars}");
            Console.WriteLine($"{CommandConvertRublesToDollars} - Конвектировать Рубли в Доллары.\n" +
                $"{CommandConvertDollarsToRubles} - Конвектировать Доллары в Рубли.\n" +
                $"{CommandConvertRublesToYuan} - Конвектировать Рубли в Юани.\n" +
                $"{CommandConvertYuanToRubles} - Конвектировать Юани в Рубли.\n" +
                $"{CommandConvertDollarsToYuan} - Конвектировать Доллары в Юани.\n" +
                $"{CommandConvertYuanToDollars} - Конвектировать Юани в Доллары.\n" +
                $"{CommandExit} - Завершить программу.");

            userInput = Console.ReadLine();

            if (userInput != CommandExit)
            {
                Console.Write("Введите количество: ");
                amountMoney = Convert.ToInt32(Console.ReadLine());
            }

            if (userInput == CommandConvertRublesToDollars || userInput == CommandConvertRublesToYuan)
            {
                if (amountMoney <= rub)
                {
                    rub -= amountMoney;
                }
                else
                {
                    userInput = CommandShowMistake;
                }
            }
            else if (userInput == CommandConvertDollarsToRubles || userInput == CommandConvertDollarsToYuan)
            {
                if (amountMoney <= dollars)
                {
                    dollars -= amountMoney;
                }
                else
                {
                    userInput = CommandShowMistake;
                }
            }
            else if (userInput == CommandConvertYuanToRubles || userInput == CommandConvertYuanToDollars)
            {
                if (amountMoney <= yuan)
                {
                    yuan -= amountMoney;
                }
                else
                {
                    userInput = CommandShowMistake;
                }
            }

            switch (userInput)
            {
                case CommandConvertRublesToDollars:
                    dollars += amountMoney * exchangeRublesToDollars;
                    break;

                case CommandConvertDollarsToRubles:
                    rub += amountMoney * exchangeDollarsToRubles;
                    break;

                case CommandConvertRublesToYuan:
                    yuan += amountMoney * exchangeRublesToYuan;
                    break;

                case CommandConvertYuanToRubles:
                    rub += amountMoney * exchangeYuanToRubles;
                    break;

                case CommandConvertDollarsToYuan:
                    yuan += amountMoney * exchangeDollarsToYuan;
                    break;

                case CommandConvertYuanToDollars:
                    dollars += amountMoney * exchangeYuanToDollars;
                    break;

                case CommandExit:
                    isWorkProgram = false;
                    Console.WriteLine("Программа завершена.");
                    break;

                case CommandShowMistake:
                    Console.WriteLine("Недостаточно средств!");
                    Console.ReadKey();
                    break;

                default:
                    Console.WriteLine("Ошибка ввода! Такой команды нет!");
                    break;
            }
        }

        Console.ReadKey();
    }
}