a-ak a-ya aaaa aaab aaac aaba aabb aabc aaby aaca aacb aacc aack aacy aaka abaa abab abac abak abay abb- abba abbb abby abca abcb abcc abyc abyy acaa acab acac acba acca accc accy akaa akay akca akka ayay ayca ayya baaa baak baba babb baby bac- baca bacc back bak- baka baya bbay bbbb bcaa bcbc bcca bccc bkcy byck caaa caab caac caba caby cac- caca cacc cack caka caky cbac cbbc cbca cbcc cbka ccaa ccab ccac ccba ccbc ccca cccb cccc ckac ckbc ckck ckcy cya- cyaa cyba cybb cybc cyc- cyca cycb cycc cyy- cyyc kaaa kaab kaak kaay kaba kabb kabc kaby kacb kacc kacy kaka kakc kakk kaya kbaa kbab kbac kbak kbay kbba kbbb kbbc kbbk kbca kbcb kbck kbcy kbkb kbkk kbky kbya kbyb kcaa kcab kcac kcba kcbc kcbk kcca kccb kccc kcck kccy kckc kckk kcky kcya kcyk kcyy kkaa kkac kkay kkba kkbb kkcb kkck kkcy kkkk kkya kkyc kkyy kyaa kyak kyay kyba kybb kybc kyby kyca kycc kyck kyka kykc kykk kyky kyya kyyk kyyy yaak yaba yacc yack yacy yaka yaya ycab yccc yyyy