<div class='user_solution'><div>a. 1. Ra5! e5 2. Rxe5 Kc6 3. Kc8</div><div><br /></div><div>3. ... Kb6 4. Kxd7 Kb7 5. Reb5#</div><div>3. ... Kd6 4. Kb8 Kc6 5. Ra6#</div><div><br /></div><div>3. ... d6? 4. Ra6#</div><div>3. ... d5? 4. Re6#</div><div><br /></div><div>b. 1. Ra5! Kc6 2. Ra6+ Kb7 3. Kxd7! Kxa6 4. Kc7 Ka7 5. Ra5#</div><div><br /></div><div>a. shows two ideal mates in full length; b. sacrifices a rook to achieve mate. The key moves are to the same square but not identical as they are different rooks and the second key grants a flight.[A]</div><div><br /></div><br /></div>