a-fu aaaa aaab aaaf aaar aaba aabb aafa aafb aaff aaoo aara aaro aaru abaa abab abaf abar abau abb- abba abbb abbo abbr abff aboa abob abof aboo abor abou abra abro abua abuf afaa afao afar affa affo afoa afoo afor afr- afra afro afru afua aoba aora aorb aouf arab araf arar arau arba arfa arfb arff arfu aroa arob aroo aror arr- arra arro arrr arru arua arub auaa aur- aura auro baaa baaf baar baba babb babo babr babu baff bafo bar- bara barb barf baro barr baru bau- bauf baur bbau bbbb boab boar boba bobb bobo bobu bofa boff bofu boob boof boor bor- bora borf boro borr boru boua bouf bour brab braf brao brau brfu broa brob broo bror brou brrr buar buba bubb bubo bubu buff bufo bufr bur- bura burb buro burr buru faaa faba fabo fabu fafa faff fafo fara farb faro farr faru faur fbar ffar ffff ffrr foaf foar foba fofo foof for- fora forb foro forr foua four frab frau frob frou frub fuar fubb fubu fuff fufu fuor fur- fura furo furr oaau oafo oara obba obbo obor obra obro off- offa offo offr offu ofor ofra ooaa ooba ooff oooo oora orab orao orar orba orbb orbo orbu orff orfu oro- orof oror orra orro orub ouff our- oura ouro ouu- raab raaf raba rabb rabo rabu rafa raff raob rara rarb rarf raro raua raub rauf rbaf rbbb rbbr roab roaf roar rob- roba robb robo robu roff rofo roob roof roor rora roro roru roua roub rouf rrrr ruba rubb rubu rufa ruff rufo rura ruro ruru uafa uaru uaua ubar ubba ubbo ubra uffa ufra uofa uofo uor- urao urau urba urfa urff uro- uroa uroo urra urur uuuu