public static void main(String[] args) {
        Scanner s = new Scanner(System.in);

        Stack<String> history = new Stack<>();
        StringBuilder current = new StringBuilder();

        int count = s.nextInt();
        for (int i = 0; i < count; i++) {
            int operation = s.nextInt();
            switch (operation) {
                case 1:
                    history.push(current.toString());
                    current.append(s.next());
                    break;
                case 2:
                    history.push(current.toString());
                    current = new StringBuilder(current.substring(0, current.length() - s.nextInt()));
                    break;
                case 3:
                    System.out.println(current.charAt(s.nextInt() - 1));
                    break;
                case 4:
                    current = new StringBuilder(history.pop());
                    break;
            }
        }
    }