Level 23 requires a different approach than other levels, I got stuck here for a long time. Maybe there should be a few similar but easier levels before it.
Hint (use rot 13 converter): Vafgrnq bs gnxvat gur xrl evtug njnl, znxr n jnyy nebhaq vg svefg
Solution (also rot13): HEQEHYHYQEQEHEQY