Normal sudoku rules apply. Digits along a blue line must have an equal sum within each 3x3 box the line passes through. (Eg r9c7 = r9c6 + r8c5 + r9c4). However every row, column, and 3x3 box contains exactly one “negator cell”. The digit in a negator cell acts as the negative of its value for the purpose of any line that passes through it (eg, a 4 in a negator cell would instead act as -4). The location of these cells must be determined. Digits in negator cells must contain all the digits 1-9 once each.