Brain Test Level 58 Stop the alien invasion

Daze Puzzle provides a complete walkthrough for "Brain Test Level 58: Stop the alien invasion!".

By Daze Puzzle /
Question
Stop the alien invasion!
Hints
Hint 1:
Don't hit the cats. There are 4 aliens.
Step 1
Answer
Tap on all of the aliens with your finger, but make sure not to tap the cats.