a-ak aaaa aaab aaac aaas aaba aabb aabc aaca aacb aacc aack aacs aaka aasa aasc aass abaa abab abac abak abas abb- abba abbb abbs abca abcb abcc abcs abs- absa abss acaa acab acac acas acba acca accc accs acks acsa acsc acss akaa akas akca akka aksa asaa asab asac asak asas asba asc- asca ascb ascc aska asks assa assc assk asss baaa baak baas baba babb babs bac- baca bacc back bacs bak- baka baks basa basc bask bass bbas bbbb bbbs bcaa bcas bcbc bcbs bcca bccc bccs bcsa bcsc bcss bsaa bsac bsas bscs bssc caaa caab caac caas caba cabs cac- caca cacc cack caka casa casb casc cask cass cbac cbbc cbbs cbca cbcc cbcs cbka cbsa cbsc ccaa ccab ccac ccas ccba ccbc ccca cccb cccc cccs ccsa ccss ckac ckbc ckck ckcs cksa cksb csaa csab csac csak csas cscb cscc cscs cska csks cssa kaaa kaab kaak kaas kaba kabb kabc kacb kacc kacs kaka kakc kakk kaks kas- kasa kasb kasc kask kass kbaa kbab kbac kbak kbas kbba kbbb kbbc kbbk kbbs kbca kbcb kbck kbcs kbkb kbkk kbsa kbsb kbsk kbss kcaa kcab kcac kcas kcba kcbc kcbk kcbs kcca kccb kccc kcck kckc kckk kcsa kcsb kcsc kcss kkaa kkac kkba kkbb kkbs kkcb kkck kkcs kkkk kksa kkss ksab ksac ksak ksas ksba ksbc ksbs ksca kscb ksck kscs kska kskb kskk ksks kssa ksss sa-c saab saac saak saas saba sabb sabc sabs saca sacc sack sacs saka sakb sakk saks sasa sasc sask sass sbaa sbac sbas sbbs sbca sbcc sbcs sbsa scaa scab scac scak scas scba sccc sccs sck- scsa scsc skab skac skss ssaa ssab ssac ssas ssca sscc sscs sssa sssb sssc ssss