-vac a-ak a-ok aaaa aaab aaac aaav aaba aabb aabc aaca aacb aacc aack aaco aacv aaka aaoo aava abaa abab abac abak abb- abba abbb abbo abca abcb abcc aboa abob abok aboo abov abva acaa acab acac acba acca accc acco acoa acvv akaa akao akca akka akko akok aoba aoca avab avao avcc avco avva avvo baaa baak baba babb babo bac- baca bacc back baco bak- baka bako bava bbbb bcaa bcbc bcca bccc bcvo boab boac boak boba bobb bobo boca bock boco boka boko boob booc book bova bovo c-bo caaa caab caac caba cabo cac- caca cacc cack caco caka cava cavo cbac cbbc cbca cbcc cbka cbko cbva cbvb ccaa ccab ccac ccba ccbc ccca cccb cccc cccv ccob ccoc ccvo ckac ckbc ckck ckco ckcv ckoa ckob ckoc ckoo ckvo coak coba cobb cobo coca cock coco cok- coka coko coob cook cova covo cvac cvca cvcc kaaa kaab kaak kaba kabb kabc kabo kacb kacc kaco kacv kaka kakc kakk kako kaoa kaoc kaok kava kavb kavo kavv kbaa kbab kbac kbak kbba kbbb kbbc kbbk kbbo kbca kbcb kbck kbco kbkb kbkk kbko kbkv kboa kbob kboc kbok kboo kbov kbva kbvb kbvc kbvo kcaa kcab kcac kcav kcba kcbc kcbk kcca kccb kccc kcck kccv kckc kckk kcko kckv kcob kcvk kcvo kcvv kkaa kkac kkba kkbb kkbo kkcb kkck kkco kkkk kkoa kkob kkoo kkov kkvv koab koac koak koba kobb kobc kobk kobo koca kocb kock koka kokb kokc kokk koko koob kooc kook kooo koov kova kovc kovk kovo kvab kvak kvbc kvcb kvcc kvck kvco kvcv kvoa kvob kvoc kvok kvoo kvov kvvv obak obba obbo obkb obok ocab ocac ocak ocbc occa occc okak okka okko okok ooaa ooak ooba oooo ovo- ovoo vaca vack vaco vaka vava vbcc voca voka vooc vovk vvob vvvv