a-ak a-ok aaaa aaab aaas aaba aabb aaka aaoo aasa aass abaa abab abak abas abb- abba abbb abbo abbs aboa abob abok aboo abos abs- absa abss akaa akao akas akka akko akok akos aksa aoba aoks aoss asaa asab asak asao asas asba asbo aska asko asks asob asok asos assa assk asso asss baaa baak baas baba babb babo babs bak- baka bako baks baos basa bask baso bass bbas bbbb bbbs boab boak boas boba bobb bobo bobs boka boko boks boob book boos bosa bosk boso boss bsaa bsas bsos k-os kaaa kaab kaak kaas kaba kabb kabo kaka kakk kako kaks kaoa kaok kaos kas- kasa kasb kask kaso kass kbaa kbab kbak kbas kbba kbbb kbbk kbbo kbbs kbkb kbkk kbko kboa kbob kbok kboo kbos kbsa kbsb kbsk kbso kbss kkaa kkba kkbb kkbo kkbs kkkk kkoa kkob kkoo kksa kkss koab koak koas koba kobb kobk kobo kobs koka kokb kokk koko koks koob kook kooo koos kos- kosa kosb koso koss ksab ksak ksas ksba ksbs kska kskb kskk ksko ksks ksob ksok ksoo ksos kssa ksso ksss oaks oass obak obas obba obbo obkb obok obos obss okak okas okka okko okok oksa okso ooaa ooak ooba oooo ooos oosa osak osas osba osoo osos ossa ossb osso s-os saab saak saas saba sabb sabo sabs saka sakb sakk sako saks saos sasa sask saso sass sbaa sbas sbbs sbsa skab skss soak soas soba sobo sobs soka sokk soko sook soos sosa soso soss ssaa ssab ssao ssas sssa sssb ssss