a-ak a-ok aaaa aaab aaar aaba aabb aaka aaoo aara aaro abaa abab abak abar abb- abba abbb abbo abbr aboa abob abok aboo abor abra abro akaa akao akar akka akko akok akr- akra aoba aora aorb arab arak arar arba arka arko aroa arob aroo aror arr- arra arrk arro arrr baaa baak baar baba babb babo babr bak- baka bako bakr bar- bara barb bark baro barr bbbb boab boak boar boba bobb bobo boka boko boob book boor bor- bora bork boro borr brab brak brao brka brkb broa brob brok broo bror brrr kaaa kaab kaak kaar kaba kabb kabo kabr kaka kakk kako kaoa kaok kaor kara karb kark karo karr kbaa kbab kbak kbar kbba kbbb kbbk kbbo kbbr kbkb kbkk kbko kbkr kboa kbob kbok kboo kbra kbrb kbrk kbro kkaa kkar kkba kkbb kkbo kkbr kkkk kkoa kkob kkoo kkor kkrb kkrk kkro kkrr koab koak koar koba kobb kobk kobo kobr koka kokb kokk koko kokr koob kook kooo koor kora korb kork koro korr krab krak krar krba krbb krbk krbr krka krkk krko krkr kroa krob krok kroo kror krrb krrk krro krrr oara obak obba obbo obkb obok obor obra obro okak okka okko okok okor okra okro ooaa ooak ooba oooo oora orab orak orao orar orba orbb orbo orka orko oro- orok oror orra orro raab raak raba rabb rabk rabo raka rakk raob raok rara rarb rark raro rbbb rbbr roab roak roar rob- roba robb robo roka rokk roko rokr roob rook roor rora rork roro rrrr