a-ak a-be aaaa aaab aaac aaae aaaf aaba aabb aabc aaca aacb aacc aace aacf aack aaea aaec aafa aafb aafc aaff aaka aake abaa abab abac abae abaf abak abb- abba abbb abbe abca abcb abcc abcf abec abee abff acaa acab acac acae acba acca accc acce accf ace- acea acec acek acfc acfe acke aeac aeaf aecb aeka afaa afak afca afcb afcc afee afek affa affc afka akaa akae akca akee akka baaa baaf baak baba babb babe bac- baca bacc bace back baek bafc baff bak- baka bake bbbb bbeb bbfc bcaa bcbc bcca bccc bcec bcfc beaf beak beba bebb bebe beca beck beeb beef beek befa befe beff beka beke bfca caaa caab caac caaf caba cabe cabf cac- caca cacc cace cack caec cafa cafb cafc cafe caff caka cake cbac cbbc cbca cbcc cbce cbea cbec cbee cbef cbfb cbfc cbka ccaa ccab ccac ccaf ccba ccbc ccca cccb cccc cccf ccee ccfa ccfc ccff ceac ceba cec- ceca cece ceeb ceec cef- cefa cefc ceke cfaa cfab cfac cfae cfbc cfca cfcb cfcf cffb ckac ckbc ckbe ckck eaaf eaba eaca eacc eaec eafb ebac ebba ebbc ebcc ebfc ecaa ecac ecbc ecbe ecca eccb eccc ecce ecef ecfa ecfc ecka eeca eeea eeee eefa eefe eeka eeke efab efca effa efke eka- ekab ekeb ekek ekfc ekka f--k faaa faac faba fabe faca facc face fack faeb fafa fafc fafe faff fake fcab fcba fcca fccf feaf feak feba fece feck feeb feek fefc fefe feff feke ffcc ffee ffff fkab kaaa kaab kaaf kaak kaba kabb kabc kabe kabf kacb kacc kace kafa kafc kafe kaff kaka kakc kake kakk kbaa kbab kbac kbae kbak kbba kbbb kbbc kbbe kbbf kbbk kbca kbcb kbce kbck kbeb kbec kbee kbef kbek kbfb kbfc kbff kbfk kbkb kbkf kbkk kcaa kcab kcac kcba kcbc kcbf kcbk kcca kccb kccc kcck kcea kceb kcec kcee kcfa kcfb kcfc kckc kckf kckk kea- keak keba kebb kebc kebe keca keck keef keek kefa kefb kefc keff keka kekb kekc keke kfab kfac kfbc kfbk kfcf kfeb kffa kffb kfff kffk kfka kfkb kkaa kkac kkba kkbb kkbe kkcb kkck kkea kkkk