#                                     ____
#    ____  ____  ____  ________  ____|Z   |____
# __|A   ||Z   ||B   ||Z       ||C             |__
#
0 1 A
2 1 A
2 1 Z
4 1 Z
4 1 B
6 1 B
6 1 Z
10 1 Z
10 1 C
12 1  Z
14 1  Z
16 1 C