a-ak aaaa aaab aaac aaal aaba aabb aabc aabl aaca aacb aacc aack aacl aaka aala aalc aall abaa abab abac abak abal abb- abba abbb abca abcb abcc abcl abla acaa acab acac acba acbl acca accc acla aclc akaa akal akca akka alaa alac alak alal alb- alba albc alca alcc alk- alka alkb all- alla alll baaa baak baal baba babb bac- baca bacc back bak- baka bakl bala balc balk ball bbbb bblb bcaa bcbc bcca bccc bccl blaa blab blac blak blkb caaa caab caac caal caba cac- caca cacc cack caka cala calc calk call cbac cbal cbbc cbca cbcc cbcl cbka cbkl cblb cblc ccaa ccab ccac ccba ccbc ccca cccb cccc cccl ccla cclc ckac ckbc ckck ckcl clab kaaa kaab kaak kaal kaba kabb kabc kacb kacc kacl kaka kakc kakk kala kalb kalc kalk kall kbaa kbab kbac kbak kbal kbba kbbb kbbc kbbk kbbl kbca kbcb kbck kbcl kbkb kbkk kbkl kbla kblb kbll kcaa kcab kcac kcal kcba kcbc kcbk kcbl kcca kccb kccc kcck kccl kckc kckk kckl kcla kclc kclk kcll kkaa kkac kkal kkba kkbb kkbl kkcb kkck kkcl kkkk kklb kklc kkll klaa klab klac klak klal klbb klbc klbl klca klcb klcc klck klcl klka klkc klkk klkl klla kllb kllc kllk laaa laac laak laal laba laca lacc lack lacl laka lala lall lbcc lcac lcbc lcca lccc lkab lkal llcc lllc llll