Another teasing miniature. The fact that it won a prize promises something out of
the ordinary.
Solution: 1.Ra8+ Kb6 2.c8Q fails to 2...Sc5+, after which there is no mate
in two. The solution is 1.Ra8+ Kb6 2.Ra6+! Kxa6, returning to the
initial position minus the rook. Now White mates in two by underpromoting:
3.c8S and after the knight moves 4.Sc5 is mate.