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