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