What are stars and ghosts?

"Stars and ghosts (children's levels)" adds a task to each maze: "Collect the stars on the way", "Keep away from the ghosts", or "Both". Two to five stars lie on the way through, evenly apart; two to four ghosts sit only in dead ends off the way, where a child is tempted. Both are checked like the maze itself. A line over each maze says what to do, for example "Collect the 5 stars on the way." and "Keep away from the ghosts.", in the book's language.