wizard poker

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Threading;

namespace ConsoleApp1
{
    class Exam
    {
        static void Main(string[] args)
        {
            List<string> letters = Console.ReadLine().Split(':').ToList();

            List<string> output = new List<string>();

            string[] command = Console.ReadLine().Split().ToArray();

            while (command[0] != "Ready")
            {
                if (command[0] == "Add")
                {
                    if (letters.Contains(command[1]))
                    {
                        output.Add(command[1]);
                    }
                    else
                    {
                        Console.WriteLine("Card not found.");
                    }
                }
                else if (command[0] == "Insert")
                {
                    int index = int.Parse(command[2]);
                    if ((index >= 0 && index < letters.Count) && index < output.Count && letters.Contains(command[1]))
                    {
                        output.Insert(index, command[1]);
                    }
                    else
                    {
                        Console.WriteLine("Error!");
                    }

                }
                else if (command[0] == "Remove")
                {
                    if (output.Contains(command[1]))
                    {
                        output.Remove(command[1]);
                    }
                    else
                    {
                        Console.WriteLine("Card not found.");
                    }
                }
                else if (command[0] == "Shuffle")
                {
                    output.Reverse();
                }
                else if (command[0] == "Swap")
                {
                    int index1 = output.IndexOf(command[1]);
                    int index2 = output.IndexOf(command[2]);

                    string tmp = output[index1];
                    output[index1] = output[index2];
                    output[index2] = tmp;

                }
                command = Console.ReadLine().Split().ToArray();
            }

            Console.WriteLine(string.Join(" ", output));
        }
    }
}