Three frogs came in through the kitchen door
Said one to the others "let's explore"
The frogs hopped in and onto the table.
They sat in a line and admired the view - the red frog on the left, the green in the middle, and the blue frog on the right.
In their excitement they hopped over each other - one frog hopping randomly over any adjacent frog.
After 999 hops they stopped!
Why I do not know - perhaps they were exhausted.
Is it possible, after their 999 hops, for them to have ended up in the position in which they started?