a-ak aaaa aaab aaas aaba aabb aaka aasa aass abaa abab abak abas abb- abba abbb abbs abs- absa abss akaa akas akka aksa asaa asab asak asas asba aska asks assa assk asss baaa baak baas baba babb babs bak- baka baks basa bask bass bbas bbbb bbbs bsaa bsas kaaa kaab kaak kaas kaba kabb kaka kakk kaks kas- kasa kasb kask kass kbaa kbab kbak kbas kbba kbbb kbbk kbbs kbkb kbkk kbsa kbsb kbsk kbss kkaa kkba kkbb kkbs kkkk kksa kkss ksab ksak ksas ksba ksbs kska kskb kskk ksks kssa ksss saab saak saas saba sabb sabs saka sakb sakk saks sasa sask sass sbaa sbas sbbs sbsa skab skss ssaa ssab ssas sssa sssb ssss