<image> The picture shows an incomplete "Sudoku". Fill in the digits for the squares where A, B, C, and D are located. A=____, B=____, C=____, D=____. (Note: "Sudoku" requires filling in the digits from 1 to 9 in a 9×9 grid such that each digit appears only once in each 3×3 bold-lined box, and each row and column of the 9×9 grid.)