> /-------\ forwardtrace: level=0
  | {}{}# |
  | AB^#+ |
  | CDv#+ |
  | {}{}# |
  \-------/
> /-------\ forwardtrace: level=1
  | {}{}+ |
  | AB^## |
  | CDv#+ |
  | {}{}# |
  \-------/
> /-------\ forwardtrace: level=2
  | {}+{} |
  | AB^## |
  | CDv#+ |
  | {}{}# |
  \-------/
> /-------\ forwardtrace: level=3
  | {}^{} |
  | ABv## |
  | CD+#+ |
  | {}{}# |
  \-------/
> /-------\ forwardtrace: level=4
  | {}^{} |
  | ABv## |
  | CD#++ |
  | {}{}# |
  \-------/
> /-------\ forwardtrace: level=5
  | {}^{} |
  | ABv## |
  | CD#+# |
  | {}{}+ |
  \-------/
> /-------\ forwardtrace: level=6
  | {}^{} |
  | ABv## |
  | CD#+# |
  | {}+{} |
  \-------/
> /-------\ forwardtrace: level=7
  | {}^{} |
  | ABv## |
  | CD++# |
  | {}#{} |
  \-------/
> /-------\ forwardtrace: level=8
  | {}+{} |
  | AB^## |
  | CDv+# |
  | {}#{} |
  \-------/
> /-------\ forwardtrace: level=9
  | {}{}+ |
  | AB^## |
  | CDv+# |
  | {}#{} |
  \-------/
> /-------\ forwardtrace: level=10
  | {}{}# |
  | AB^#+ |
  | CDv+# |
  | {}#{} |
  \-------/
> /-------\ forwardtrace: level=11
  | {}{}# |
  | AB^## |
  | CDv++ |
  | {}#{} |
  \-------/
> /-------\ forwardtrace: level=12
  | {}{}# |
  | AB^## |
  | CDv{} |
  | {}#++ |
  \-------/
> /-------\ forwardtrace: level=13
  | {}{}# |
  | AB^## |
  | CDv{} |
  | {}+#+ |
  \-------/
> /-------\ forwardtrace: level=14
  | {}{}# |
  | AB+## |
  | CD^{} |
  | {}v#+ |
  \-------/
> /-------\ forwardtrace: level=15
  | {}{}# |
  | AB#+# |
  | CD^{} |
  | {}v#+ |
  \-------/
> /-------\ forwardtrace: level=16
  | {}{}# |
  | AB##+ |
  | CD^{} |
  | {}v#+ |
  \-------/
> /-------\ forwardtrace: level=17
  | {}{}+ |
  | AB### |
  | CD^{} |
  | {}v#+ |
  \-------/
> /-------\ forwardtrace: level=18
  | {}+{} |
  | AB### |
  | CD^{} |
  | {}v#+ |
  \-------/
> /-------\ forwardtrace: level=19
  | {}#{} |
  | AB+## |
  | CD^{} |
  | {}v#+ |
  \-------/
> /-------\ forwardtrace: level=20
  | {}#{} |
  | AB^## |
  | CDv{} |
  | {}+#+ |
  \-------/
> /-------\ forwardtrace: level=21
  | {}#{} |
  | AB^## |
  | CDv{} |
  | +{}#+ |
  \-------/
> /-------\ forwardtrace: level=22
  | {}#{} |
  | AB^## |
  | CDv{} |
  | +{}+# |
  \-------/
> /-------\ forwardtrace: level=23
  | {}#{} |
  | AB^## |
  | CDv{} |
  | ++{}# |
  \-------/
> /-------\ forwardtrace: level=24
  | {}#{} |
  | ++^## |
  | ABv{} |
  | CD{}# |
  \-------/
> /-------\ forwardtrace: level=25
  | ++#{} |
  | {}^## |
  | ABv{} |
  | CD{}# |
  \-------/
> /-------\ forwardtrace: level=26
  | +#+{} |
  | {}^## |
  | ABv{} |
  | CD{}# |
  \-------/
> /-------\ forwardtrace: level=27
  | #++{} |
  | {}^## |
  | ABv{} |
  | CD{}# |
  \-------/
> /-------\ forwardtrace: level=28
  | #+{}+ |
  | {}^## |
  | ABv{} |
  | CD{}# |
  \-------/
> /-------\ forwardtrace: level=29
  | #{}++ |
  | {}^## |
  | ABv{} |
  | CD{}# |
  \-------/
> /-------\ forwardtrace: level=30
  | #{}#+ |
  | {}^+# |
  | ABv{} |
  | CD{}# |
  \-------/
> /-------\ forwardtrace: level=31
  | #{}## |
  | {}^++ |
  | ABv{} |
  | CD{}# |
  \-------/
> /-------\ forwardtrace: level=32
  | #{}## |
  | {}^{} |
  | ABv++ |
  | CD{}# |
  \-------/
> /-------\ forwardtrace: level=33
  | #{}## |
  | {}^{} |
  | ABv+# |
  | CD{}+ |
  \-------/
> /-------\ forwardtrace: level=34
  | #{}## |
  | {}^{} |
  | ABv#+ |
  | CD{}+ |
  \-------/
> /-------\ forwardtrace: level=35
  | #{}## |
  | {}^{} |
  | ABv#+ |
  | CD+{} |
  \-------/
> /-------\ forwardtrace: level=36
  | #{}## |
  | {}+{} |
  | AB^#+ |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=37
  | #{}## |
  | {}{}+ |
  | AB^#+ |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=38
  | #{}#+ |
  | {}{}# |
  | AB^#+ |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=39
  | #{}#+ |
  | {}{}+ |
  | AB^## |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=40
  | #{}#+ |
  | {}+{} |
  | AB^## |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=41
  | #{}#+ |
  | +{}{} |
  | AB^## |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=42
  | +{}#+ |
  | #{}{} |
  | AB^## |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=43
  | {}+#+ |
  | #{}{} |
  | AB^## |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=44
  | {}#++ |
  | #{}{} |
  | AB^## |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=45
  | {}#{} |
  | #{}++ |
  | AB^## |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=46
  | {}#{} |
  | #+{}+ |
  | AB^## |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=47
  | {}#{} |
  | #++{} |
  | AB^## |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=48
  | {}+{} |
  | #+#{} |
  | AB^## |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=49
  | {}+{} |
  | ##+{} |
  | AB^## |
  | CDv{} |
  \-------/
> /-------\ forwardtrace: level=50
  | {}+{} |
  | ##^{} |
  | ABv## |
  | CD+{} |
  \-------/
> /-------\ forwardtrace: level=51
  | {}^{} |
  | ##v{} |
  | AB+## |
  | CD+{} |
  \-------/
> /-------\ forwardtrace: level=52
  | {}^{} |
  | ##v{} |
  | AB+## |
  | CD{}+ |
  \-------/
> /-------\ forwardtrace: level=53
  | {}^{} |
  | ##v{} |
  | AB+#+ |
  | CD{}# |
  \-------/
> /-------\ forwardtrace: level=54
  | {}^{} |
  | ##v{} |
  | AB++# |
  | CD{}# |
  \-------/
> /-------\ forwardtrace: level=55
  | {}^{} |
  | ##v{} |
  | AB{}# |
  | CD++# |
  \-------/
> /-------\ forwardtrace: level=56
  | {}^{} |
  | ##v{} |
  | AB{}# |
  | CD+#+ |
  \-------/
> /-------\ forwardtrace: level=57
  | {}^{} |
  | ##v{} |
  | AB{}+ |
  | CD+## |
  \-------/
> /-------\ forwardtrace: level=58
  | {}^{} |
  | ##v{} |
  | AB+{} |
  | CD+## |
  \-------/
> /-------\ forwardtrace: level=59
  | {}+{} |
  | ##^{} |
  | ABv{} |
  | CD+## |
  \-------/
> /-------\ forwardtrace: level=60
  | +{}{} |
  | ##^{} |
  | ABv{} |
  | CD+## |
  \-------/
> /-------\ forwardtrace: level=61
  | #{}{} |
  | +#^{} |
  | ABv{} |
  | CD+## |
  \-------/
> /-------\ forwardtrace: level=62
  | #{}{} |
  | #+^{} |
  | ABv{} |
  | CD+## |
  \-------/
> /-------\ forwardtrace: level=63
  | #{}{} |
  | #++{} |
  | AB^{} |
  | CDv## |
  \-------/
> /-------\ forwardtrace: level=64
  | #{}{} |
  | #+{}+ |
  | AB^{} |
  | CDv## |
  \-------/
> /-------\ forwardtrace: level=65
  | #{}{} |
  | #{}++ |
  | AB^{} |
  | CDv## |
  \-------/
> /-------\ forwardtrace: level=66
  | #{}{} |
  | #{}{} |
  | AB^++ |
  | CDv## |
  \-------/
> /-------\ forwardtrace: level=67
  | #{}{} |
  | #{}{} |
  | AB^#+ |
  | CDv+# |
  \-------/
> /-------\ forwardtrace: level=68
  | #{}{} |
  | #{}{} |
  | AB^+# |
  | CDv+# |
  \-------/
> /-------\ forwardtrace: level=69
  | #{}{} |
  | #{}{} |
  | AB+^# |
  | CD+v# |
  \-------/
> /-------\ forwardtrace: level=70
  | #{}{} |
  | #{}{} |
  | +AB^# |
  | +CDv# |
  \-------/
> /-------\ forwardtrace: level=71
  | #{}{} |
  | +{}{} |
  | #AB^# |
  | +CDv# |
  \-------/
> /-------\ forwardtrace: level=72
  | +{}{} |
  | #{}{} |
  | #AB^# |
  | +CDv# |
  \-------/
> /-------\ forwardtrace: level=73
  | {}+{} |
  | #{}{} |
  | #AB^# |
  | +CDv# |
  \-------/
> /-------\ forwardtrace: level=74
  | {}{}+ |
  | #{}{} |
  | #AB^# |
  | +CDv# |
  \-------/
> /-------\ forwardtrace: level=75
  | {}{}+ |
  | #{}{} |
  | +AB^# |
  | #CDv# |
  \-------/
> /-------\ forwardtrace: level=76
  | {}{}+ |
  | +{}{} |
  | #AB^# |
  | #CDv# |
  \-------/
> /-------\ forwardtrace: level=77
  | {}{}+ |
  | {}+{} |
  | #AB^# |
  | #CDv# |
  \-------/
> /-------\ forwardtrace: level=78
  | {}{}+ |
  | {}{}+ |
  | #AB^# |
  | #CDv# |
  \-------/
> /-------\ forwardtrace: level=79
  | {}{}+ |
  | {}{}# |
  | #AB^+ |
  | #CDv# |
  \-------/
> /-------\ forwardtrace: level=80
  | {}{}# |
  | {}{}+ |
  | #AB^+ |
  | #CDv# |
  \-------/
> /-------\ forwardtrace: level=81
  | {}{}# |
  | {}{}+ |
  | #AB^# |
  | #CDv+ |
  \-------/
> /-------\ forwardtrace: level=82
  | {}{}# |
  | {}{}# |
  | #AB^+ |
  | #CDv+ |
  \-------/
> /-------\ forwardtrace: level=83
  | {}{}# |
  | {}{}# |
  | #AB+^ |
  | #CD+v |
  \-------/
> /-------\ forwardtrace: level=84
  | {}{}# |
  | {}{}# |
  | #+AB^ |
  | #+CDv |
  \-------/
> /-------\ forwardtrace: level=85
  | {}{}# |
  | {}{}# |
  | +#AB^ |
  | #+CDv |
  \-------/
> /-------\ forwardtrace: level=86
  | {}{}# |
  | {}{}# |
  | ++AB^ |
  | ##CDv |
  \-------/
> /-------\ forwardtrace: level=87
  | {}{}# |
  | ++{}# |
  | {}AB^ |
  | ##CDv |
  \-------/
> /-------\ forwardtrace: level=88
  | {}{}# |
  | +{}+# |
  | {}AB^ |
  | ##CDv |
  \-------/
> /-------\ forwardtrace: level=89
  | {}{}# |
  | {}++# |
  | {}AB^ |
  | ##CDv |
  \-------/
> /-------\ forwardtrace: level=90
  | {}{}# |
  | {}AB# |
  | {}CD^ |
  | ##++v |
  \-------/
> /-------\ forwardtrace: level=91
  | {}{}# |
  | {}AB# |
  | {}CD^ |
  | #+#+v |
  \-------/
> /-------\ forwardtrace: level=92
  | {}{}# |
  | {}AB# |
  | {}CD^ |
  | +##+v |
  \-------/
> /-------\ forwardtrace: level=93
  | {}{}# |
  | {}AB# |
  | {}CD^ |
  | +#+#v |
  \-------/
> /-------\ forwardtrace: level=94
  | {}{}# |
  | {}AB# |
  | {}CD^ |
  | ++##v |
  \-------/
> /-------\ forwardtrace: level=95
  | {}{}# |
  | {}AB# |
  | ++CD^ |
  | {}##v |
  \-------/
> /-------\ forwardtrace: level=96
  | {}{}# |
  | ++AB# |
  | {}CD^ |
  | {}##v |
  \-------/
> /-------\ forwardtrace: level=97
  | ++{}# |
  | {}AB# |
  | {}CD^ |
  | {}##v |
  \-------/
> /-------\ forwardtrace: level=98
  | +{}+# |
  | {}AB# |
  | {}CD^ |
  | {}##v |
  \-------/
> /-------\ forwardtrace: level=99
  | {}++# |
  | {}AB# |
  | {}CD^ |
  | {}##v |
  \-------/
> /-------\ forwardtrace: level=100
  | {}AB# |
  | {}CD# |
  | {}++^ |
  | {}##v |
  \-------/
> /-------\ forwardtrace: level=101
  | {}AB# |
  | {}CD# |
  | {}#+^ |
  | {}+#v |
  \-------/
> /-------\ forwardtrace: level=102
  | {}AB# |
  | {}CD# |
  | {}#+^ |
  | {}#+v |
  \-------/
> /-------\ forwardtrace: level=103
  | {}AB# |
  | {}CD# |
  | {}#^+ |
  | {}#v+ |
  \-------/
> /-------\ forwardtrace: level=104
  | {}AB# |
  | {}CD+ |
  | {}#^# |
  | {}#v+ |
  \-------/
> /-------\ forwardtrace: level=105
  | {}AB+ |
  | {}CD# |
  | {}#^# |
  | {}#v+ |
  \-------/
> /-------\ forwardtrace: level=106
  | {}AB+ |
  | {}CD# |
  | {}#^+ |
  | {}#v# |
  \-------/
> /-------\ forwardtrace: level=107
  | {}AB+ |
  | {}CD+ |
  | {}#^# |
  | {}#v# |
  \-------/
> /-------\ forwardtrace: level=108
  | {}+AB |
  | {}+CD |
  | {}#^# |
  | {}#v# |
  \-------/
> /-------\ forwardtrace: level=109
  | {}+AB |
  | {}#CD |
  | {}+^# |
  | {}#v# |
  \-------/
> /-------\ forwardtrace: level=110
  | {}#AB |
  | {}+CD |
  | {}+^# |
  | {}#v# |
  \-------/
> /-------\ forwardtrace: level=111
  | {}#AB |
  | {}+CD |
  | {}#^# |
  | {}+v# |
  \-------/
> /-------\ forwardtrace: level=112
  | {}#AB |
  | {}#CD |
  | {}+^# |
  | {}+v# |
  \-------/
> /-------\ forwardtrace: level=113
  | {}#AB |
  | {}#CD |
  | {}^+# |
  | {}v+# |
  \-------/
> /-------\ forwardtrace: level=114
  | {}#AB |
  | {}#CD |
  | {}^#+ |
  | {}v+# |
  \-------/
> /-------\ forwardtrace: level=115
  | {}#AB |
  | {}#CD |
  | {}^++ |
  | {}v## |
  \-------/
> /-------\ forwardtrace: level=116
  | {}#++ |
  | {}#AB |
  | {}^CD |
  | {}v## |
  \-------/