Sudoku #3781

Complexity: Extremely Hard

 Fun Fact About Sudoku
The First World Sudoku Championship was held in Italy in 2006 and has been held annually since in different locations.

Enter numbers into the empty cells so that each row, column and 3x3 box contains the numbers 1 to 9.

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