a-ak a-ii aaaa aaab aaac aaai aaba aabb aabc aabi aaca aacb aacc aaci aack aaib aaic aaii aaka abaa abab abac abai abak abb- abba abbb abbi abca abcb abcc abci abia abib abic acaa acab acac acai acba acca accc acci aci- acia acic aiai aiba aica aicc aiia aiib aiic aika aiki akaa akai akca akia akik akka akki ba-i baaa baak baba babb babi bac- baca bacc baci back baia baib baic baik bak- baka baki bbbb bbci bcaa bcbc bcca bccc bcci bcia biak biba bibb bibi bica bicc bici bick caaa caab caac caba cabi cac- caca cacc caci cack caia caib caic caik caka cbac cbbc cbca cbcc cbia cbka ccaa ccab ccac ccai ccba ccbc ccca cccb cccc ccci ccic ccii ciaa ciak ciba cibc cibi cica cicc cici ciia ciii cika ckac ckbc ckbi ckck iaaa iaac iaai iaba iaca iacc iaia ibac ibca ibia icaa icab icac icai icbc icca iccb iccc icci iiac iica iiii ikki k-ci kaaa kaab kaai kaak kaba kabb kabc kabi kacb kacc kaci kaia kaib kaic kaii kaik kaka kakc kaki kakk kbaa kbab kbac kbai kbak kbba kbbb kbbc kbbi kbbk kbca kbcb kbci kbck kbia kbib kbic kbik kbkb kbkk kcaa kcab kcac kcai kcba kcbc kcbi kcbk kcca kccb kccc kcci kcck kcic kcii kckc kckk kiab kiac kiai kiba kibb kibc kibi kica kicb kicc kick kiia kiic kiii kiik kika kikc kiki kikk kkaa kkac kkai kkba kkbb kkbi kkcb kkci kkck kkia kkic kkik kkkk