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