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Twin Problem 3: Mate in 2 Moves

(White: Kg8, Rf5, Rg6, Bh7, Na4, Ne2, Black: Kb1, Ra1, Nc2, Nd3, a2, g7.)

White to move and mate in 2

Now, remove black pawn h5:

(White: Kg8, Rf5, Rg6, Bh7, Na4, Ne2, Black: Kb1, Ra1, Nc2, Nd3, a2, c7.)

White to move and mate in 2

Solution:

(a) 1. Rc5! Nd4 2. Rg1# 
(b) 1. Rc6! N2e1 2. Rb5#