SimpleTextEditor

namespace SimpleTextEditor
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;

    public class SimpleTextEditor
    {
        public static void Main()
        {
            int n = int.Parse(Console.ReadLine());
            Stack<string> myStack = new Stack<string>();
            string str = "";
            myStack.Push(str);

            for (int i = 0; i < n; i++)
            {
                string[] command =
                    Console.ReadLine()
                    .Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries)
                    .ToArray();

                switch (command[0])
                {
                    case "1":
                        {
                            str += command[1];
                            myStack.Push(str);
                        }
                        break;

                    case "2":
                        {
                            int elementsToErase = int.Parse(command[1]);
                            str = str.Substring(0, str.Length - elementsToErase);
                            myStack.Push(str);
                        }
                        break;

                    case "3":
                        {
                            int indexToPrint = int.Parse(command[1]);
                            Console.WriteLine(str[indexToPrint - 1]);
                        }
                        break;

                    case "4":
                        {
                            myStack.Pop();
                            str = myStack.Peek();
                        }
                        break;
                }
            }
        }
    }
}