123. 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 43 legal first moves and exactly one of them works. 18 pieces, Black 49 to Red 11 in material, mate by the cannon. Themes: the cannon fires over a black piece, the general w…