public class Solution {
 public static void main(String[] args) {
       Scanner in=new Scanner(System.in);
       int n=in.nextInt();
       String s = "";
      Stack<String> st =new Stack<String>();
      st.push(s);
        for(int i=0;i<n;i++){
        	 int t=in.nextInt();
            if(t==1){ s = s+in.next();st.push(s);
               }
            else if(t==2){s=s.substring(0,s.length()-in.nextInt());st.push(s);}
            else if(t==3){System.out.println(s.charAt(in.nextInt()-1)); }
            else{st.pop();s=st.peek();}}}}