Place a digit from 0 to 6 into some cells so that no digit appears more than once in each row or column. Cells may remain empty. Numbers outside the grid indicate all sums of continuous groups of digits (including “sums” of a single digit) along that row or column. These groups are separated by empty cells (a cell with 0 is not considered empty). These sums are given in the same order as their corresponding groups of digits.