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.
5
3
4
4
6
8
1
4
3
6
4
1
2
5
6
3
6
7
2
5
1
9
2
6
7
5
***** Extreme