Correct answer: Nd51...Nb6/Rb5/Ra7/Rc7/Rd7/Re7/Rf7/Rg7/Rh7 2.Qb5# 1.Nb6?? (2.Qb5#) 1...Nc7 2.Bd7# but 1...R:b6! 1.Bd7+??
