a-ak a-ok aaaa aaab aaar aaba aabb aaka aaoo aara aaro abaa abab abak abar abax abb- abba abbb abbo abbr aboa abob abok aboo abor abox abra abro akaa akao akar akka akko akok akr- akra aoba aora aorb arab arak arar arax arba arka arko aroa arob aroo aror arr- arra arrk arro arrr axar axo- axoa axxo ba-x baaa baak baar baba babb babo babr bak- baka bako bakr bar- bara barb bark baro barr barx bbbb bbox boab boak boar boba bobb bobo boka boko boob book boor boox bor- bora bork boro borr boxa brab brak brao brax brka brkb broa brob brok broo bror brox brrr kaaa kaab kaak kaar kaba kabb kabo kabr kaka kakk kako kakx kaoa kaok kaor kaox kara karb kark karo karr karx kaxa kbaa kbab kbak kbar kbba kbbb kbbk kbbo kbbr kbkb kbkk kbko kbkr kboa kbob kbok kboo kbox kbra kbrb kbrk kbro kbrx kbxb kbxr kbxx kkaa kkar kkba kkbb kkbo kkbr kkkk kkoa kkob kkoo kkor kkrb kkrk kkro kkrr kkrx kkxa kkxk kkxx koab koak koar koba kobb kobk kobo kobr koka kokb kokk koko kokr kokx koob kook kooo koor kora korb kork koro korr koxr krab krak krar krba krbb krbk krbr krbx krka krkk krko krkr krkx kroa krob krok kroo kror krox krrb krrk krro krrr krrx krxa krxb krxk krxo krxr krxx kxaa kxar kxba kxbr kxbx kxkk kxkx kxoa kxok kxoo kxor kxox kxra kxrb kxrk kxro kxrr kxrx kxxk kxxo kxxr kxxx oara obak obba obbo obkb obok obor obox 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 oxa- oxo- oxox oxxo raab raak raba rabb rabk rabo raka rakk raob raok rara rarb rark raro raxa rbbb rbbr roab roak roar rob- roba robb robo roka rokk roko rokr roob rook roor roox rora rork roro roxa roxo rrrr xaar xara xbar xbox xbra xoka xoro xoxo xxxo xxxx