try(Scanner scan = new Scanner(System.in)){

	int n = scan.nextInt();
	scan.nextLine();

	Stack<String> history = new Stack<>();
	String text="" ;

	for (int i = 0; i < n; i++) {
		int command = scan.nextInt();
		switch(command){
			case 1:
			history.push(text);
			text+=scan.nextLine().trim();
			break;
			case 2:
			history.push(text);
			text = text.substring(0, text.length()-scan.nextInt());
			break;
			case 3:
			System.out.println(text.charAt(scan.nextInt()-1));
			break;
			case 4:
			text= history.pop(); 
			break;                    
		}
	}
}