Level 22. I'm too tired to keep playing.
Also, FUCK level 21. The boxes change place (seemingly at random) every time you die. I don't know if you're REQUIRED to die or not, but I know there were some setups that were literally impossible (one time, I had no way to go from the start that didn't end up with an instant loss).
Just, fuck that level.
Edit: Level 24. Level 22 was deceptively easy (6 moves, I think). Level 24 sucks.