Divide the grid into nine regions, each consisting of nine orthogonally-connected cells. Regions cannot overlap. Place the digits 1-9 once in each row, column, and region. Each region has a corresponding colour. A note outside the grid indicates that the region of that colour contains a run of one or more orthogonally-connected cells (bounded on either side by a region border or the edge of the grid) in that row or column, and the number in the note (if given) is the sum of the digits in these cells. If a region contains multiple sets of orthogonally-connected cells in the same row or column, a note only applies to one of them. When two notes overlap, the note above has a lower sum than the note below (this applies even if a sum is hidden or not given).