Zeroes are dots here.
See there are 4 all-zero
and 8 non-zero groups.
16 groups are all together.
The rest is easy. There are
exactly 16-4-8=4 mixed.
.... .... .... ....
...1 .a5d 3a61 7..c
ac19 d3d6 6bfa 793.
965e cd4c 2779 d998
3880 seconds no block
