a-a a-b aaa aab aad aak aao aar aau ab- aba abb abd abk abo abr abu ad- ada adb add adk ado adr adu aka akb akd akk ako akr aku aoa aob aod aok aoo aor aou ar- ara arb ard ark aro arr aru au- aua aub aud auk auo aur b-u baa bab bad bak bao bar bau bba bbb bbd bbk bbo bbr bbu bda bdb bdd bdk bdo bdr bdu bka bkb bkk bko bkr boa bob bod bok boo bor bou bra brb brd brk bro brr bru bua bub bud buk buo bur buu daa dab dad dak dao dar dau dba dbb dbd dbk dbo dbr dbu dda ddb ddd ddk ddo ddr ddu dka dkb dkk dko dkr dku doa dob dod dok doo dor dou dra drb drd drk dro drr dru dua dub dud duk duo dur ka- kaa kab kad kak kao kar kau kba kbb kbd kbk kbo kbr kbu kda kdb kdk kdo kdr kdu kkb kkk kkr kku koa kob kod kok koo kor kou kra krd krk kro krr kru kub kud kuk kur kuu oaa oab oad oak oao oar oau ob- oba obb obd obk obo obr obu oda odb odd odo odr odu oka okb okd okk oko okr oku oo- ooa oob ood ook ooo oor or- ora orb ord ork oro orr oru ou- oua oud ouk ouo our ra- raa rab rad rak rao rar rau rba rbb rbd rbk rbo rbr rbu rda rdb rdd rdo rdr rdu rkb rkk rko rku roa rob rod rok roo ror rou rra rrb rrd rrk rrr rru rua rub rud ruk ruo rur ruu ua- uaa uab uad uak uao uar uau uba ubb ubk ubo ubr ubu uda udb udd udk udo udr udu uka ukb ukk ukr uku uoa uob uod uok uoo uor ur- ura urb urd urk uro urr uru uua uur uuu