import java.io.*;
import java.util.*;

class Operation {
    int type;
    String value;
    public Operation(int type, String value) {
        this.type = type;
        this.value = value;
    }
}

public class Solution {
    
    private static StringBuilder text = new StringBuilder("");
    
    // trace append and delete operations
    private static Stack<Operation> trace = new Stack<>(); 
    
    public static void main(String[] args) {
        
        Scanner scan = new Scanner(System.in);
        int q = scan.nextInt();
        for(int i = 0; i < q; i++) {
        int operation = scan.nextInt();
       
            switch(operation) {
                case 1:
                String newText = scan.next();
                trace.push(new Operation(1, newText));
                add(newText);
                break;
                
                case 2:
                int numToDelete = scan.nextInt();
                int textLen = text.length();
                trace.push(new Operation(2, text.substring(textLen - numToDelete, textLen)));
                delete(numToDelete);
                break;
                
                case 3:
                int indextToPrint = scan.nextInt();
                System.out.println(text.charAt(indextToPrint-1));
                break;
 
                case 4:
                undo();
                break;
            }
        }
        scan.close();
    }
    
    
    private static void delete(int numToDelete) {
        int textLen = text.length();
        String tempText = text.substring(0, textLen - numToDelete);
        text.setLength(0);
        text.append(tempText);
    }
    
    private static void add(String newText) {
        text.append(newText);
    }
    
    private static void undo() {
        if(!trace.isEmpty()) {
            Operation lastOperation = trace.pop();
            if(lastOperation.type == 1) {
                delete(lastOperation.value.length());
            } else {
                add(lastOperation.value);
            }
        }
    }
}