using System;
using System.Collections.Generic;

namespace Problem09SimpleTextEditor
{
    class Program
    {
        static void Main(string[] args)
        {
            int numberOfOperations = int.Parse(Console.ReadLine());


            string result = string.Empty;
            Stack<string> stack = new Stack<string>();

            for (int i = 1; i <= numberOfOperations; i++)
            {
                string[] currentCommand = Console.ReadLine()
                    .Split(" ", StringSplitOptions.RemoveEmptyEntries);

                if (currentCommand[0] == "1")
                {
                    stack.Push(result);
                    string stringToAppend = currentCommand[1];
                    result += stringToAppend;
                }
                else if (currentCommand[0] == "2")
                {
                    stack.Push(result);

                    int count = int.Parse(currentCommand[1]);
                    if (result.Length >= count)
                    {
                        string substringToRemove = string.Empty;
                        for (int j = result.Length - count; j < result.Length; j++)
                        {
                            substringToRemove += result[j];
                        }
                        result = result.Replace(substringToRemove, "");
                    }

                }
                else if (currentCommand[0] == "3")
                {
                    int index = int.Parse(currentCommand[1]);

                    Console.WriteLine(result[index - 1]);
                }
                else if (currentCommand[0] == "4")
                {
                    if (stack.Count > 0)
                    {
                        result = stack.Pop();
                    }
                    else
                    {
                        result = string.Empty;
                    }
                }
            }
        }
    }
}