a-ak a-ok aaaa aaab aaac aaba aabb aabc aaca aacb aacc aack aaco aaka aaoo abaa abab abac abak abax abb- abba abbb abbo abca abcb abcc aboa abob abok aboo abox acaa acab acac acba acca accc acco acoa akaa akao akca akka akko akok aoba aoca axo- axoa axxo ba-x baaa baak baba babb babo bac- baca bacc back baco bak- baka bako bbbb bbox bcaa bcbc bcca bccc boab boac boak boba bobb bobo boca bock boco boka boko boob booc book boox boxa c-bo caaa caab caac caba cabo cac- caca cacc cack caco caka caxa cbac cbax cbbc cbca cbcc cbka cbko cbox cbxa ccaa ccab ccac ccba ccbc ccca cccb cccc ccob ccoc ckac ckbc ckbx ckck ckco ckcx ckoa ckob ckoc ckoo coak coax coba cobb cobo coca cock coco cok- coka coko coob cook coxa cxxx kaaa kaab kaak kaba kabb kabc kabo kacb kacc kaco kaka kakc kakk kako kakx kaoa kaoc kaok kaox kaxa kbaa kbab kbac kbak kbba kbbb kbbc kbbk kbbo kbca kbcb kbck kbco kbkb kbkk kbko kboa kbob kboc kbok kboo kbox kbxb kbxx kc-x kcaa kcab kcac kcba kcbc kcbk kcbx kcca kccb kccc kcck kckc kckk kcko kckx kcob kcox kkaa kkac kkba kkbb kkbo kkcb kkck kkco kkkk kkoa kkob kkoo kkxa kkxk kkxx koab koac koak koba kobb kobc kobk kobo koca kocb kock koka kokb kokc kokk koko kokx koob kooc kook kooo koxc kxaa kxac kxba kxbx kxca kxkc kxkk kxkx kxoa kxok kxoo kxox kxxk kxxo kxxx obak obba obbo obkb obok obox ocab ocac ocak ocbc occa occc okak okka okko okok ooaa ooak ooba oooo oxa- oxo- oxox oxxo xbox xobc xoca xoco xoka xoxo xxxo xxxx