a-ak a-ok aaaa aaab aaac aaar aaba aabb aabc aaca aacb aacc aack aaco aacr aaka aaoo aara aarc aaro abaa abab abac abak abar abb- abba abbb abbo abbr abca abcb abcc abcr aboa abob abok aboo abor abra abrc abro acaa acab acac acar acba acca accc acco acoa acor acr- acra acrc acro acrr akaa akao akar akca akka akko akok akr- akra aoba aoca aora aorb arab arac arak arar arba arc- arca arco arka arko aroa arob aroo aror arr- arra arrc arrk arro arrr baaa baak baar baba babb babo babr bac- baca bacc back baco bak- baka bako bakr bar- bara barb barc bark baro barr bbbb bbrc bcaa bcar bcbc bcca bccc bcor bcra boab boac boak boar boba bobb bobo boca bock boco boka boko boob booc book boor bor- bora bork boro borr brab brac brak brao brca brcb brka brkb broa brob broc brok broo bror brrr c-bo caaa caab caac caba cabo cac- caca cacc cack caco cacr caka caor cara carb carc cark caro carr cbac cbar cbbc cbca cbcc cbcr cbka cbko cbkr ccaa ccab ccac ccar ccba ccbc ccca cccb cccc ccob ccoc ccra ccrc ckac ckbc ckck ckco ckoa ckob ckoc ckoo ckor ckrc coak coba cobb cobo coca cock coco cok- coka coko coob cook cor- cora corb corc cork coro corr crab crac crar crbc crca crcc crcr crkc crob croc crok croo cror kaaa kaab kaak kaar kaba kabb kabc kabo kabr kacb kacc kaco kaka kakc kakk kako kaoa kaoc kaok kaor kara karb kark karo karr kbaa kbab kbac kbak kbar kbba kbbb kbbc kbbk kbbo kbbr kbca kbcb kbck kbco kbcr kbkb kbkk kbko kbkr kboa kbob kboc kbok kboo kbra kbrb kbrc kbrk kbro kcaa kcab kcac kcar kcba kcbc kcbk kcbr kcca kccb kccc kcck kccr kckc kckk kcko kckr kcob kcor kcrc kcro kcrr kkaa kkac kkar kkba kkbb kkbo kkbr kkcb kkck kkco kkcr kkkk kkoa kkob kkoo kkor kkrb kkrc kkrk kkro kkrr koab koac koak koar koba kobb kobc kobk kobo kobr koca kocb kock koka kokb kokc kokk koko kokr koob kooc kook kooo koor kora korb korc kork koro korr krab krac krak krar krba krbb krbk krbr krca krcb krcc krco krka krkc krkk krko krkr kroa krob kroc krok kroo kror krrb krrc krrk krro krrr oara obak obba obbo obkb obok obor obra obro ocab ocac ocak ocbc occa occc ocra ocro ocrr okak okka okko okok okor okra okro ooaa ooak ooba oocr oooo oora orab orac orak orao orar orba orbb orbo orca orco orka orko oro- orok oror orra orro raab raak raba rabb rabk rabo rac- raca racc rack raco raka rakk raob raoc raok rara rarb rark raro rbbb rbbr rcac rcbc rcbo rccb rccc roab roak roar rob- roba robb robo roca rocc rock roco roka rokk roko rokr roob rook roor rora rorc rork roro rrrr