SUDOKU
Write a number from 1 to 9 into each empty square in the grid so that every number from 1 to 9 appears exactly once in each horizontal row, each vertical column, and each 3×3 block.
4
3
2
5
8
4
2
7
3
7
1
3
3
9
1
6
4
5
4
6
8
7
9
9
1
5
***** Extreme