Place a number from 1 to 9 in each cell, such that for any two horizontal neighbours, the number between and above the two is their sum or their difference. In gray rows, all numbers must be distinct, while in white rows, there must be at least one pair of duplicate numbers.

If an edge between horizontal neighbours is marked with a white dot, the difference between the two numbers is 1. If it is marked with a black dot, one number is double the other number. If there is no mark, neither of the above conditions apply.