603128
1A 2C 3D 4A 5A 6A7C 9A 11A12C 13A 14A17A
1C 2B 4D 6C 7D 10B 12C 13B 14D 15D 16B 17
cdada
cdaab
acbdd
b
18t19t
A C D A A A C B A B A C A A B B A B XX