159. the cannon fires over a black piece, by the cannon

Helpmates in xiangqi

4 moves

Black moves first and both sides cooperate: Black, Red, Black, Red, and Red's second move mates. Black has 2 legal first moves and exactly one of them works. 16 pieces, Black 38 to Red 11 in material, mate by the cannon. Themes: the cannon fires over a black piece, a piece alread…