远程数独

Fill each cell — even the ones with grey numbers — with a digit between 1 and 9 so that each row, column, and outlined 3-by-3 squares contains each digit once.

A grey number N indicates that there is an N exactly N squares away (horizontally or vertically).

The answer to this month’s puzzle is the sum of the squares of the numbers written over the gray numbers in the completed grid.

(For example, if a 7 is written over one of the grey numbers, that would contribute 49 towards the sum.)