Each row, column, and 9-cell region must contain the digits 1-9 once each. The regions must be determined by the solver. Each region must be coloured in its entirety with a single colour. No two regions of the same colour may share an edge, and at most four distinct colours may be used. Cells containing arrows give the distance to the nearest cell of the same colour in each indicated direction (neighbouring cells are a distance 1 from each other). All possible arrows are given.