a-ak aaaa aaab aaac aaad aaar aaba aabb aabc aabd aaca aacb aacc aacd aack aacr aada aadc aaka aara aarc aard abaa abab abac abad abak abar abb- abba abbb abbr abca abcb abcc abcd abcr abda abra abrc acaa acab acac acad acar acba acca accc accd acda acdb acdc ackd acr- acra acrc acrr adaa adab adac adad adak adar adba adbc adcc adda addc addd addr adra akaa akar akca akka akr- akra arab arac arad arak arar arba arc- arca arda ardc arka arr- arra arrc arrk arrr baaa baad baak baar baba babb babr bac- baca bacc back bada badb badd badr bak- baka bakr bar- bara barb barc bard bark barr bbad bbbb bbdd bbrc bcaa bcar bcbc bcca bccc bcda bcra bd-r bdbc bddc brab brac brad brak brca brcb brda brka brkb brrr c-cd caaa caab caac caba cac- caca cacc cack cacr cada cadc cadd cadr caka cara carb carc card cark carr cbac cbar cbbc cbca cbcc cbcr cbdb cbdc cbka cbkr cbrd ccaa ccab ccac ccad ccar ccba ccbc ccca cccb cccc ccdc ccdr ccra ccrc cd-r cdaa cdac cdad cdba cdda cddb cddr ckac ckbc ckck ckrc ckrd crab crac crar crbc crca crcc crcr crda crdc crkc daab daad daar daba dabb daca dada daka dara darb darc dard dark darr dbar dbcc dcbc dcca dccb dccc dcdb dcra dcrk dddd ddrc dkba dkdc draa drab drac drad drak drar drba drbc drca drda drra kaaa kaab kaak kaar kaba kabb kabc kabd kabr kacb kacc kacd kad- kada kadd kadr kaka kakc kakk kara karb kard kark karr kbaa kbab kbac kbad kbak kbar kbba kbbb kbbc kbbd kbbk kbbr kbca kbcb kbck kbcr kbdb kbdr kbkb kbkk kbkr kbra kbrb kbrc kbrd kbrk kcaa kcab kcac kcad kcar kcba kcbc kcbd kcbk kcbr kcca kccb kccc kccd kcck kccr kcda kcdc kcdd kcdr kckc kckk kckr kcrc kcrr kdaa kdab kdac kdad kdak kdar kdbb kdbr kdca kdcc kdcd kdcr kddb kddc kddd kddk kddr kdka kdkb kdkd kdkk kdkr kdrb kkaa kkac kkar kkba kkbb kkbd kkbr kkcb kkcd kkck kkcr kkda kkdc kkdd kkkk kkrb kkrc kkrk kkrr krab krac krad krak krar krba krbb krbd krbk krbr krca krcb krcc krcd krda krdc krdd krdr krka krkc krkd krkk krkr krrb krrc krrk krrr raab raad raak raba rabb rabk rac- raca racc rack rada radc radd radr raka rakk rara rarb rark rbbb rbbr rcac rcbc rccb rccc rcdc rcrd rdac rrad rrrr