Every 3 minutes for as long as possible complete:

From 0:00-3:00

2 rounds of:

10 overhead squats (43 / 29kg.)
10 chest-to-bar pull-ups

From 3:00-6:00

2 rounds of:

12 overhead squats ( 43 / 29kg.)

12 chest-to-bar pull-ups

From 6:00-9:00

2 rounds of:

14 overhead squats (43 / 29kg.)

14 chest-to-bar pull-ups

Etc., following same pattern until you fail to complete both rounds