diagrammes 60, 01/1983
15+15. Mate in 1
Analysis: Queens did not move and have been captured at home (by enemy Knights). Kings and Rooks only performed oscillations. All in all we can check that White played an odd number of move while Black played an even number of moves (the old parity argument). Thus White did move last and Black is to move.
Mate in 1: 1 ... Na1xc2 # and not the illegal 1. Nxf7??.