Revise paste ДЗ: Конвертер валют

using System;
using System.Data;

internal class Program
{
    static void Main(string[] args)
    {
        const string CommandConvertRubToUsd = "1";
        const string CommandConvertUsdToRub = "2";
        const string CommandConvertRubToEur = "3";
        const string CommandConvertEurToRub = "4";
        const string CommandConvertEurToUsd = "5";
        const string CommandConvertUsdToEur = "6";
        const string CommandExit = "7";

float rubInWallet = 10000f;
        float usdInWallet = 300f;
        float eurInWallet = 0f;
        bool isWork = true;

while (isWork)
        {
            Console.Clear();
            Console.WriteLine($"На счете:\nРубли - {rubInWallet}\nДоллары - {usdInWallet}\nЕвро - {eurInWallet}");
            Console.ReadKey();

Console.WriteLine($"{CommandConvertRubToUsd}" +
                $"\n{CommandConvertUsdToRub}" +
                $"\n{CommandConvertRubToEur}" +
                $"\n{CommandConvertEurToRub}" +
                $"\n{CommandConvertUsdToEur}" +
                $"\n{CommandConvertEurToUsd}" +
                $"\n{CommandExit} - Завершить программу.");

string userInput = Console.ReadLine();

switch (userInput)
            {
                case CommandConvertRubToUsd:

break;

case CommandConvertUsdToRub:

break;

case CommandConvertRubToEur:

break;

case CommandConvertEurToRub:

break;

case CommandConvertEurToUsd:
                    break;

case CommandConvertUsdToEur:
                    break;

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

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

Console.ReadKey();
    }
}