Then there are all the ones of the form, you are at a river with a boat that can carry you plus one other person, other animal, or other thing. One one bank there are three cannibals, three missionaries, and three fried chickens. If you leave more cannibals than missionaries the cannibals will eat the missionaries; if you leave more missionaries than fried chickens the missionaries will eat the fried chickens. How do you get all 9 across? Cannibals don't eat fried chicken, and fried chickens don't eat anything.