a-ak a-be aaaa aaab aaac aaae aaaf aaar aaba aabb aabc aaca aacb aacc aace aacf aack aacr aaea aaec aafa aafb aafc aaff aaka aake aara aarc aare abaa abab abac abae abaf abak abar abb- abba abbb abbe abbr abca abcb abcc abcf abcr abec abee aber abff abra abrc acaa acab acac acae acar acba acca accc acce accf ace- acea acec acek acer acfc acfe acke acr- acra acrc acre acrr aeac aeaf aecb aeer aeka aer- aera aerc afaa afak afar afca afcb afcc afee afek afer affa affc afka afkr afr- afra afrc afre akaa akae akar akca akee aker akka akr- akra akre arab arac arae araf arak arar arba arbe arc- arca arce area arec aree aref arek arfa arfb arfc arff arka arke arr- arra arrc arre arrk arrr baaa baaf baak baar baba babb babe babr bac- baca bacc bace back baek baer bafc baff bak- baka bake bakr bar- bara barb barc bare barf bark barr bbbb bbeb bbfc bbrc bcaa bcar bcbc bcca bccc bcec bcer bcfc bcra beaf beak bear beba bebb bebe beca beck beeb beef beek beer befa befe beff beka beke bera berc bere berk berr bfca brab brac brae braf brak brca brcb brce brea breb brec bree bref brek brer brfc brka brkb brrr caaa caab caac caaf caba cabe cabf cac- caca cacc cace cack cacr caec caer cafa cafb cafc cafe caff caka cake cara carb carc care carf cark carr cbac cbar cbbc cbca cbcc cbce cbcr cbea cbec cbee cbef cber cbfb cbfc cbka cbkr cbre ccaa ccab ccac ccaf ccar ccba ccbc ccca cccb cccc cccf ccee ccfa ccfc ccff ccra ccrc ccre ccrf ceac cear ceba cec- ceca cece ceeb ceec cef- cefa cefc ceke cer- cera cerc cere cerf cfaa cfab cfac cfae cfar cfbc cfbr cfca cfcb cfcf cffb cffr cfra cfrb cfre ckac ckbc ckbe ckck cker ckfr ckrc crab crac craf crar crbc crca crcc crce crcr cre- crea creb crec cree crfc crkc eaaf eaba eaca eacc eaec eafb eara earb eare ebac ebba ebbc ebbr ebcc eber ebfc ecaa ecac ecar ecbc ecbe ecca eccb eccc ecce ecef ecfa ecfc ecfr ecka ecra ecrc ecrf ecrr eeca eeea eeee eefa eefe eeka eeke eera eerc efab efbr efca effa efke eka- ekab ekeb ekek eker ekfc ekka eraf erba erbb erbe erca ercc erce ereb erec erer erfc erke erra errc erre f--k faaa faac faba fabe faca facc face fack faeb fafa fafc fafe faff fake fara farb farc fare fark farr fbar fcab fcar fcba fcca fccf fcra feaf feak fear feba fece feck feeb feek feer fefc fefe feff feke fera ferb ferc fere ferk ferr ffar ffcc ffee ffff ffrr fkab frab frac frae frak frbc frcc frea free frfc kaaa kaab kaaf kaak kaar kaba kabb kabc kabe kabf kabr kacb kacc kace kaer kafa kafc kafe kaff kafr kaka kakc kake kakk kara karb kare karf kark karr kbaa kbab kbac kbae kbak kbar kbba kbbb kbbc kbbe kbbf kbbk kbbr kbca kbcb kbce kbck kbcr kbeb kbec kbee kbef kbek kber kbfb kbfc kbff kbfk kbfr kbkb kbkf kbkk kbkr kbra kbrb kbrc kbre kbrf kbrk kcaa kcab kcac kcar kcba kcbc kcbf kcbk kcbr kcca kccb kccc kcck kccr kcea kceb kcec kcee kcfa kcfb kcfc kckc kckf kckk kckr kcrc kcrr kea- keak kear keba kebb kebc kebe kebr keca keck kecr keef keek keer kefa kefb kefc keff kefr keka kekb kekc keke ker- kera kerb kerc kere kerf kerk kerr kfab kfac kfar kfbc kfbk kfcf kfcr kfeb kfer kffa kffb kfff kffk kfka kfkb kfra kfrc kfre kfrr kkaa kkac kkar kkba kkbb kkbe kkbr kkcb kkck kkcr kkea kkfr kkkk kkrb kkrc kkre kkrf kkrk kkrr krab krac krae krak krar krba krbb krbe krbk krbr krca krcb krcc krce krea kreb krec kree kref krek krfc krfe krff krka krkc krke krkk krkr krrb krrc krre krrf krrk krrr raab raaf raak raba rabb rabe rabk rac- raca racc race rack raec raef raer rafa rafc rafe raff raka rake rakk rara rarb rare rarf rark rbaf rbbb rbbr rcac rcaf rcbc rccb rccc rcfc rea- reac reae reaf reak rear reba rebb rebe rebk reca recc rece reck recr reeb reef reek refe reff refr reka reke rera rere rfae rfef rffc rkkf rrfc rrrr