a a a b b c c c
a b b b b c c c
a b b b b b c c
b b b b b c c c
b b b d e c c c
b b b e e e c c
b b e e e e f f
b b b e e f f f
b b b e e f f f
b b b b b b f f
b b b g g h h h
b b g g h h h h
i i j g k k k k
i i j k k k k k
i i j j k k k k
i i i k k k k k
i i k k k k k k
i k k k k k k k
i k k k k k k k
l l k k k k k k
m m m m m m m m
m m m m m m m m
m m m m m m m m
m m m m m m m m
