by steps
000000 000000
000000
737676 737676
737676
00007f 00007f
00007f
0000ff 0000ff
0000ff
007f00 007f00
007f00
007f7f 007f7f
007f7f
667676 667676
667676
007fff 007fff
007fff
00ff00 00ff00
00ff00
00ff7f 00ff7f
00ff7f
597777 597777
597777
00ffff 00ffff
00ffff
7f0000 7f0000
7f0000
7f007f 7f007f
7f007f
4d7878 4d7878
4d7878
7f00ff 7f00ff
7f00ff
7f7f00 7f7f00
7f7f00
7f7f7f 7f7f7f
7f7f7f
407979 407979
407979
7f7fff 7f7fff
7f7fff
7fff00 7fff00
7fff00
7fff7f 7fff7f
7fff7f
7fffff 7fffff
7fffff
337a7a 337a7a
337a7a
ff0000 ff0000
ff0000
ff007f ff007f
ff007f
ff00ff ff00ff
ff00ff
277b7b 277b7b
277b7b
ff7f00 ff7f00
ff7f00
ff7f7f ff7f7f
ff7f7f
ff7fff ff7fff
ff7fff
1a7c7c 1a7c7c
1a7c7c
ffff00 ffff00
ffff00
ffff7f ffff7f
ffff7f
ffffff ffffff
ffffff
0e7d7d 0e7d7d
0e7d7d