Place a digit from 1-7 in each cell. Each digit must appear exactly once in each row, column, and box, except for the digits 1 and 3, which may appear any positive number of times. Every 1 and 3 must be part of at least one adjacent pair of cells which reads as '13' either from left to right or from top to bottom. Digits in a cage do not repeat (including 1 and 3) and sum to the total shown in the top left corner.