Once upon a time there was a farmer who bought a fox, a goose, and a bag of corn. Transporting them home, she came to a river and borrowed a boat. But the boat was small and the farmer could carry only herself and one of the purchases: the fox, the goose, or the corn.

If left together unattended, fox would eat goose, or goose would eat corn.

How does the farmer get everything across the river intact?