is a logic puzzle invented by Nikoli. A rectangular or square grid contains 3 kinds of symbols: cross, horizontal bar, vertical bar. The goal is to divide the grid into rectangular regions. Each region contains one cell with a symbol. - A region with a cross must be a square. - If a region contains a horizontal bar, the region's width must be greater than its height. - If a region contains a vertical bar, the region's width must be less than its height. - A grid dot must not be shared by the corners of four regions.