Mainplan: 1.g6? Rh5#!
Try play: 1.Ra4? bxa4 (Bxa4) 2.g6 Rh5+ 3.Kf4 Rc4#!
Try play: 1.Ra4 bxa4 (Bxa4) 2.Bd6? cxd6 3.g6 Rh5+ 4.Kf4 Rc4+ 5.Kg3 Sf1#! (if 5…Rh7 6.gxh7? 7.Sf1#!)
Solution (C+):
Foreplan A 1.Ra2! Bxa2
Foreplan B 2.Ra4 bxa4
Foreplan C 3.Bd6 cxd6
Mainplan 4.g6 Rh5+ 5.Kf4 Rc4+ 6.Kg3 Sf1+ 7.Kg2 Rc2+ 8.Kg1 Rg2+ 9.Kxg2 Rg5 10.hxg5 ~ 11.g7# MM (if 9…Rh7 10.gxh7 ~11.h8=Q/R#)
