public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner input = new Scanner(System.in);
        StringBuffer sb = new StringBuffer("");
        int q = input.nextInt();
        Stack<String> deletedString = new Stack<>();
        Stack<String> appendedString = new Stack<>();
        Stack<Integer> trace = new Stack<>();
        
        for(int j = 0; j < q; j++){
            int choose = input.nextInt();
            switch(choose){
                case 1:
                    String str = input.next();
                    sb.append(str);
                    appendedString.push(str);
                    trace.push(1);
                    break;
                case 2:
                    int k = input.nextInt();
                    int startIndex = Math.max(0, sb.length() - k);
                    deletedString.push(sb.substring(startIndex));
                    sb.delete(startIndex, sb.length());
                    trace.push(2);
                    break;
                case 3:
                    int i = input.nextInt();
                    if(i > 0 && i <= sb.length()){
                        System.out.println(sb.charAt(i - 1));
                    }
                    break;
                case 4:
                    if(!trace.isEmpty()){
                        int operate = trace.pop();
                        if(operate == 1){
                            String string = appendedString.pop();
                            sb.delete(sb.length() - string.length(), sb.length());
                        }
                        else if(operate == 2){
                            String string2 = deletedString.pop();
                            sb.append(string2);
                        }
                    }
                    
                    break;
                    
            }
        }
        input.close();
    }
}