Table:
text: 2007 Roger Federer tennis season
Singles: 12 (8–4)
Singles: 12 (8–4)
Outcome No_ Date_ Championship Surface Opponent_in_the_final Score_in_the_final
Winner 51. September 9, 2007 US Open, New York City, United States (4) Hard Novak Djokovic 7–6 (7–4) , 7–6 (7–2) , 6–4
Runner-up 17. October 21, 2007 Madrid, Spain Hard (i) David Nalbandian 6–1, 3–6, 3–6
Winner 52. October 28, 2007 Basel, Switzerland (2) Hard (i) Jarkko Nieminen 6–3, 6–4

text: 2007 Roger Federer tennis season
Singles: 12 (8–4)
Singles: 12 (8–4)
Outcome No_ Date_ Championship Surface Opponent_in_the_final Score_in_the_final
Winner 46. January 28, 2007 Australian Open, Melbourne, Australia (3) Hard Fernando González 7–6 (7–2) , 6–4, 6–4
Winner 47. March 3, 2007 Dubai, United Arab Emirates (4) Hard Mikhail Youzhny 6–4, 6–3
Winner 48. May 20, 2007 Hamburg, Germany (4) Clay Rafael Nadal 2–6, 6–2, 6–0
Runner-up 15. June 10, 2007 French Open, Paris, France (2) Clay Rafael Nadal 3–6, 6–4, 3–6, 4–6
Winner 49. July 8, 2007 Wimbledon, London, England, UK (5) Grass Rafael Nadal 7–6 (9–7) , 4–6, 7–6 (7–3) , 2–6, 6–2

Question: From Roger Federer's 2007 tennis season list where the result is winner and the surface is hard (i), what is the number?