collecting keys

on my game i want the allien to be able to collect a certian amount of keys. When he collects them all he wins the game. Pls help. I need a pic

http://flowlab.io/game/play/42148

how about a simple example.
Collision (key) — (+) number — filter (greater than 4) — next level
Collect 5 keys to go to the next level.