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

public class Solution {

public static void main(String[] args) throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    int n = Integer.parseInt(br.readLine());
    String outputString = "";
    Stack<String> stack = new Stack<>();
    stack.push(outputString);
    List<Character> result = new ArrayList<>();
    for (int i = 0; i < n; i++) {
        String append = null;
        int show = 0;
        int del = 0;
        String inp = br.readLine();
        String arr[] = inp.split(" ");
        int opt = Integer.parseInt(arr[0]);
        switch (opt) {
        case 1:
            append = arr[1];
            outputString += append;
            stack.push(outputString);
            break;
        case 2:
            del = Integer.parseInt(arr[1]);
            outputString = outputString.substring(0, outputString.length() - del);
            stack.push(outputString);
            break;
        case 3:
            show = Integer.parseInt(arr[1]);
            result.add(outputString.charAt(show - 1));
            break;
        case 4:
            stack.pop();
            outputString = stack.peek();
        }
    }
    try {
        for(Character j:result)
            System.out.println(j);
    } catch (Exception e) {

    }
}

}