I skipped day 18. Why? Because the workout at the gym was more than enough abs....
4 rounds for time of 500m row and L-Sit. So it if takes you 2:30 to row a 500m you now have 2:30 of L-sit to accumulate. I alternated between pull-up bar L-Sit, ring L-sit, box L-sit and finally hollow holds(boats) on the ground. Then afterward we had a cash out of 50-100 situps. I chose to do 25 GHDs and that was more than enough. It was hard getting out of bed this morning.