a-a a-b aaa aab aad aao aar aau ab- aba abb abd abo abr abu ad- ada adb add ado adr adu aoa aob aod aoo aor aou ar- ara arb ard aro arr aru au- aua aub aud auo aur b-u baa bab bad bao bar bau bba bbb bbd bbo bbr bbu bda bdb bdd bdo bdr bdu boa bob bod boo bor bou bra brb brd bro brr bru bua bub bud buo bur buu daa dab dad dao dar dau dba dbb dbd dbo dbr dbu dda ddb ddd ddo ddr ddu doa dob dod doo dor dou dra drb drd dro drr dru dua dub dud duo dur oaa oab oad oao oar oau ob- oba obb obd obo obr obu oda odb odd odo odr odu oo- ooa oob ood ooo oor or- ora orb ord oro orr oru ou- oua oud ouo our ra- raa rab rad rao rar rau rba rbb rbd rbo rbr rbu rda rdb rdd rdo rdr rdu roa rob rod roo ror rou rra rrb rrd rrr rru rua rub rud ruo rur ruu ua- uaa uab uad uao uar uau uba ubb ubo ubr ubu uda udb udd udo udr udu uoa uob uod uoo uor ur- ura urb urd uro urr uru uua uur uuu