0:      1:      2:      3:      4:
 _aaaa_    ....    _aaaa    aaaa_    ....
_b    c_  .    _c_  .    _c_  .    _c  b    c_
_b    c_  .    _c_  .    _c_  .    _c  b    c_
 ....    ....    _dddd    dddd    dddd_
_e    f_  .    _f  e_    .  .    _f_  .    _f_
_e    f_  .    _f  e_    .  .    _f_  .    _f_
 _gggg_    ....    _gggg    gggg_    ....

  5:      6:      7:      8:      9:
 _aaaa    aaaa    aaaa    aaaa    aaaa_
_b_    .  _b_    .  .    _c  b    c  b    c_
_b_    .  _b_    .  .    _c  b    c  b    c_
 _dddd    dddd_    ....    _dddd    dddd_
.    _f  e    f_  .    _f  e    f_  .    _f_
.    _f  e    f_  .    _f  e    f_  .    _f_
 _gggg    gggg_    ....    _gggg    gggg_