Puzzle of the Day 17 June 2016 |  Find the best move

1. Ra4 Nc6 2. Ra2 Na7 3. Kb4 Nc6+ 4. Kc3 Ka7 5. Ra3 Kb6 6. Ra4 Na7 7. Kd4 Kb5 8. Ra3 Kb6 9. Kd5 Kb5