Where are my mates?

• Normal sudoku rules apply, i.e. each row, column and 3x3 region has to contain the digits from 1 to 9 once each.

• Dutch Flat Mates: Each 5 in the grid either has a 1 directly above or a 9 directly below it. (It may have both, but it does not need both.)

• Outside Sum + Sandwich: Each clue outside the grid indicates the sum of all the digits in its row or column up to the first 1 or 9. (The bounding 1 or 9 is not part of that sum.)

Moreover, each outside clue is a Sandwich clue, i.e. it indicates the sum of all digits between 1 and 9 in the respective row or column.

• Arrows: A digit in a cell containing a small blue arrow indicates the distance to the next 1 or 9 in that direction.