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