Puzzle of the Day 1 August 2016 |  Find the best move

1. a8=Q Rxa8 2. Kg6 Rg8+ 3. Kh7 Rc8 4. Kg6 Rc1 5. a7 Rg1+ 6. Kh7 Ra1 7. Kg8 Rxa7 8. h7 Kf5 9. h8=Q Ra8+ 10. Kh7 Rxh8+ 11. Kxh8 Kf4 12. Kg7 Kg4 13. Kg8 Kh4 14. Kh7 Kg4 15. Kg8