Three nurses and three cannibals want to get to the other side of a river.
There is a small boat, which can fit only two. To prevent a tragedy, there can never be more cannibals than nurses together.
How will they do to get to the other side of the river?
1 cannibal and 1 nurse there, nurse back.
2 cannibals there, 1 cannibal back.
2 nurses there, 1 nurse and 1 cannibal back.
2 nurses there, 1 cannibal back.
This one cannibal takes the remaining cannibals to the other side.