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