N4, black has three legal moves:

- RxN RxR, N5 (unique), RxN 1-0

- R5, R2 RxN (if R6, NxR, 1-0), RxR N5 (unique), RxN, 1-0

... N5 NxR+ K7 (unique), R4 KxN (if N3+, K2 N5, N8 KxN, RxN 1-0), R2 K7 (or N3, RxN 1-0), RxN (1-0)