Rabbits and Trees (also known as "Raitonanba", "Light Number") is a square grid with numbers in some cells. The task is to place exactly one white circle ("rabbit") and one black circle ("tree") in every row and every column. A number indicates how many white circles ("rabbits") can be seen in the corresponding row and column. A rabbit is visible only when it is not hidden behind a tree.
Cross+A can solve puzzles from 5 x 5 to 20 x 20.