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