a-ak a-be aaaa aaab aaac aaae aaba aabb aabc aaca aacb aacc aace aack aaea aaec aaka aake abaa abab abac abae abak abb- abba abbb abbe abca abcb abcc abec abee acaa acab acac acae acba acca accc acce ace- acea acec acek acke aeac aecb aeka akaa akae akca akee akka baaa baak baba babb babe bac- baca bacc bace back baek bak- baka bake bbbb bbeb bcaa bcbc bcca bccc bcec beak beba bebb bebe beca beck beeb beek beka beke caaa caab caac caba cabe cac- caca cacc cace cack caec caka cake cbac cbbc cbca cbcc cbce cbea cbec cbee cbka ccaa ccab ccac ccba ccbc ccca cccb cccc ccee ceac ceba cec- ceca cece ceeb ceec ceke ckac ckbc ckbe ckck eaba eaca eacc eaec ebac ebba ebbc ebcc ecaa ecac ecbc ecbe ecca eccb eccc ecce ecka eeca eeea eeee eeka eeke eka- ekab ekeb ekek ekka kaaa kaab kaak kaba kabb kabc kabe kacb kacc kace kaka kakc kake kakk kbaa kbab kbac kbae kbak kbba kbbb kbbc kbbe kbbk kbca kbcb kbce kbck kbeb kbec kbee kbek kbkb kbkk kcaa kcab kcac kcba kcbc kcbk kcca kccb kccc kcck kcea kceb kcec kcee kckc kckk kea- keak keba kebb kebc kebe keca keck keek keka kekb kekc keke kkaa kkac kkba kkbb kkbe kkcb kkck kkea kkkk