a-ak aaaa aaab aaac aaaf aaal aaba aabb aabc aabl aaca aacb aacc aacf aack aacl aafa aafb aafc aaff aafl aaka aala aalc aall abaa abab abac abaf abaj abak abal abb- abba abbb abca abcb abcc abcf abcl abff abla ablj acaa acab acac acba acbl acca accc accf acfc acfl acla aclc afaa afak afca afcb afcc affa affc afka afla aflc ajab ajac ajak ajba ajka ajkf ajla akaa akal akca akka alaa alac alak alal alb- alba albc alca alcc alfa alk- alka alkb all- alla alll baaa baaf baak baal baba babb bac- baca bacc back bafc baff baja bak- baka bakl bala balc balf balk ball bbbb bbfc bblb bcaa bcbc bcca bccc bccl bcfc bfca bffl bjcc blaa blab blac blaj blak blfc blkb caaa caab caac caaf caal caba cabf cac- caca cacc cack cafa cafb cafc caff cafl caja caka cala calc calf calk call cbac cbal cbbc cbca cbcc cbcl cbfb cbfc cbka cbkj cbkl cblb cblc ccaa ccab ccac ccaf ccba ccbc ccca cccb cccc cccf cccl ccfa ccfc ccff ccfl ccla cclc cfaa cfab cfac cfbc cfca cfcb cfcf cfcl cffb cjbc cjbk cjca cjcb cjcj cjcl cjfb cjfl ckac ckbc ckck ckcl cklf clab claf f--k faaa faac faba faca facc fack fafa fafc faff faja fala falc falk fall fbla fcab fcal fcba fcca fccf fccj ffcc ffff fjca fkab flab flac flak flcl jaaf jaak jaal jaba jaca jacc jack jacl jafa jafc jaff jaja jaka jala jalc jbaa jcbc jccc jjcc jklf jlab kaaa kaab kaaf kaak kaal kaba kabb kabc kabf kacb kacc kacl kafa kafc kaff kaja kajb kajc kajk kaka kakc kakj kakk kala kalb kalc kalf kalk kall kbaa kbab kbac kbak kbal kbba kbbb kbbc kbbf kbbk kbbl kbca kbcb kbck kbcl kbfb kbfc kbff kbfk kbfl kbja kbjc kbjk kbkb kbkf kbkk kbkl kbla kblb kblf kblj kbll kcaa kcab kcac kcal kcba kcbc kcbf kcbk kcbl kcca kccb kccc kcck kccl kcfa kcfb kcfc kcfj kcfl kcjb kcjc kcjf kcjj kcjk kckc kckf kckj kckk kckl kcla kclc kclf kclk kcll kfab kfac kfal kfbc kfbk kfcf kffa kffb kfff kffk kfjb kfjc kfjk kfka kfkb kfla kflb kflc kflf kfll kjaa kjac kjak kjal kjbb kjbl kjcb kjcc kjck kjff kjfk kjjf kjjj kjjk kjjl kjkj kjkk kjla kjll kkaa kkac kkal kkba kkbb kkbj kkbl kkcb kkcj kkck kkcl kkjb kkjk kkjl kkkj kkkk kklb kklc kklf kkll klaa klab klac klaf klaj klak klal klbb klbc klbf klbj klbl klca klcb klcc klck klcl klfa klfc klff klfj klja kljb klka klkc klkk klkl klla kllb kllc kllk laaa laac laaj laak laal laba laca lacc lack lacl lafb lafc laff laja laka lala lall lbcc lcac lcbc lcca lccc lcfc lfca lfcc ljla lkab lkal llcc lllc llll