# 1: bl to tr via tl [*/]
# 2: tl to br via tr [\*]
# 3: tr to bl via br [/.]
# 4: br to tl via bl [.\]
# C,N,NE,E,SE,S,SW,W,NW,C'
# 003
# 012
# 340
# A) w must be 1, nw/n must be 0 for c to be 2
00xxxxx102
# B) n must be 1, nw/w must be 0 for c to be 4
01xxxxx004
# C) ne must be 1, n/e must be 0 for c to be 3
0010xxxxx3
# D) sw must be 1, s/w must be 0 for c to be 3
0xxxx010x3
# generalization
# C)
0010xxxxx3
0xx020xxx4
0xxxx030x1
00xxxxx042
# D)
0xxxx010x3
00xxxxx024
0030xxxxx1
0xx040xxx2
# A)
00xxxxx102
0200xxxxx3
0xx300xxx4
0xxxx400x1
# B)
01xxxxx004
0002xxxxx1
0xx003xxx2
0xxxx004x3