Tabatta this Workout

8 rounds, 20 seconds of chosen exercise, 10 seconds rest:

Pull-ups....10,7,6,6,6,5,5,5
push ups....9,9,9,9,9,8,8,8
sit-ups....10,10,10,10,10,10,10,10
squats....17,15,15,15,15,15,15,15