Sudoku #3218

Complexity: Extremely Hard

 Fun Fact About Sudoku
British Airways absolutely forbids its flight attendants from solving Sudoku puzzles during either takeoff or landing.

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

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