Normal sudoku rules apply. On renban lines (purple), digits on the line cannot repeat, and form a set of consecutive digits in some order. On German whisper lines (green), adjacent digits differ by at least 5. On region sum lines (blue), each time the line passes through a 3x3 region, the sum of digits on the line is the same. Each line is exactly one of the above constraint types, but some have been drawn in the wrong colour. The wrong-coloured lines are exactly those lines which have the digit D on them (D must be determined by the solver).