Correct answer: Rc51...Kf5 2.N:d4# 1...f5 2.Bf7# 1.Re3+?? 1...Kf5 2.N:d4# 1...K:d5 2.Bf3# but 1...d:e3! 1.R:e7+?? 1...Kf5 2.N:d4# but 1...K