bbbb bobb bobo boko boob book boor booz bor- bork boro borr borz bovo bozo brkb brob brok broo bror broz brrr bzrk bzzz kbbb kbbk kbbo kbbr kbbz kbkb kbkk kbko kbkr kbkv kbkz kbob kbok kboo kbov kboz kbrb kbrk kbro kbrv kbrz kbvb kbvo kbvr kbzo kbzz kkbb kkbo kkbr kkbz kkkk kkob kkoo kkor kkov kkoz kkrb kkrk kkro kkrr kkrv kkrz kkvr kkvv kkzz kobb kobk kobo kobr kokb kokk koko kokr kokz koob kook kooo koor koov kooz korb kork koro korr korv kovk kovo kovr kozb kozk kozo kozr krbb krbk krbr krbz krkk krko krkr krkv krkz krob krok kroo kror krov kroz krrb krrk krro krrr krrz krvb krvk krvo krvr krvv krvz krzk krzr krzz kvbr kvbz kvob kvok kvoo kvor kvov kvoz kvro kvrr kvrv kvvr kvvv kvvz kzbb kzbk kzbr kzbv kzbz kzkr kzkz kzoo kzor kzoz kzrb kzrk kzro kzrr kzrv kzrz kzzb kzzk kzzo kzzr kzzv kzzz obbo obkb obok obor obro okko okok okor okro oooo orbb orbo orko oro- orok oror oroz orro orvr orzk orzo ovo- ovoo rbbb rbbr rob- robb robo rokk roko rokr roob rook roor rooz rork roro rovo rozz rrrr vkor vkzv voor vor- voro vovk vvob vvvv z-ro zobo zoo- zook zorb zork zoro zovk zozo zzzz