Wataridori (from Japanese, literally "migratory birds") is a logic puzzle published by Nikoli. A rectangular or square grid is divided into regions. A grid contains circles (empty or with numbers) in some cells. The aim is to connect circles in pairs by drawing a line that goes horizontally and vertically through the centers of cells. A cell may be visited by a line at most once. A line may connect circles with equal numbers, empty circles, or a line may be drawn between an empty circle and a circle with a number. A number in a circle indicates how many regions are visited by the line. A region may be visited by the line at most once.
Cross+A can solve puzzles from 3 x 3 to 30 x 30.