#include <bits/stdc++.h>
#define lli long long int
using namespace std;

int main() {

    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    
    stack<char> s;
    stack<string> undo;
    
    lli tc;
    cin >> tc;
    while(tc--) {
        lli x;
        cin >> x;
        if (x == 1) {
            // insert
            string v;
            cin >> v;

            string temp = "";
            if (!undo.empty()) {
                temp = undo.top();
            }
            for (int i = 0; i < v.length(); i++) {
                temp += v[i];
                s.push(v[i]);
            }
            undo.push(temp);
        } else if (x == 2) {
            if (s.empty()) continue;
            // delete
            lli y;
            cin >> y;
            while(y--) {
                s.pop();
            }
            string ab = "";
            stack<char> temp;
            temp = s;
            while(!temp.empty()) {
                ab += temp.top();
                temp.pop();
            }
            if (ab.length() > 0) reverse(ab.begin(), ab.end());
            undo.push(ab);
        } else if (x == 3) {
            if (s.empty()) continue;
            // print
            lli y;
            cin >> y;
            string temp = undo.top();
            cout << temp[y-1] << "\n";
        } else {
            // undo
            if (!undo.empty()) {
                undo.pop();
                string temp = "";
                if (!undo.empty()) temp = undo.top();
                s = stack<char>();
                for (auto it: temp) {
                    s.push(it);
                }
            }
        }
    }
    
    return 0;
}