Puzzle of the Day 29 July 2016 |  Find the best move

1. a6 Ra1 2. Kb5 h4 3. Bg4 Kf6 4. Kb6 Ke5 5. a7 Kd6 6. Kb7 Rb1+ 7. Kc8 Rc1+ 8. Kb8 Rb1+ 9. Kc8