namespace _Simple_Text_Editor
{
    using System;
    using System.Collections.Generic;
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());

            string manipulete = string.Empty;

            Stack<string> operations = new Stack<string>();

            for (int i = 0; i < n; i++)
            {
                string[] command = Console.ReadLine()
                    .Split(" ".ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
                if (command[0] == "1")
                {
                    operations.Push(manipulete);
                    manipulete += command[1];

                }
                else if (command[0] == "2" &&
                    int.Parse(command[1]) <= manipulete.Length)
                {
                    operations.Push(manipulete);
                    manipulete = manipulete.Remove(manipulete.Length - int.Parse(command[1]), int.Parse(command[1]));

                }
                else if (command[0] == "3" &&
                    int.Parse(command[1]) > 0 &&
                    int.Parse(command[1]) - 1 < manipulete.Length)
                {
                    Console.WriteLine(manipulete[int.Parse(command[1]) - 1]);
                }
                else if (command[0] == "4")
                {
                    manipulete = operations.Pop();
                }
            }
        }
    }
}