a-a a-b aaa aab aad aaf aao aar aau ab- aba abb abd abf abo abr abu ad- ada adb add adf ado adr adu af- afa afb afd aff afo afr afu aoa aob aod aof aoo aor aou ar- ara arb ard arf aro arr aru au- aua aub aud auf auo aur b-u baa bab bad baf bao bar bau bba bbb bbd bbf bbo bbr bbu bda bdb bdd bdf bdo bdr bdu bfa bfb bfd bff bfo bfr bfu boa bob bod bof boo bor bou bra brb brd brf bro brr bru bua bub bud buf buo bur buu daa dab dad daf dao dar dau dba dbb dbd dbf dbo dbr dbu dda ddb ddd ddf ddo ddr ddu dfa dfb dfd dff dfo dfr dfu doa dob dod dof doo dor dou dra drb drd dro drr dru dua dub dud duf duo dur faa fab fad faf fao far fau fba fbb fbd fbf fbo fbr fbu fda fdb fdd fdf fdo fdr fdu ffa ffd fff ffo ffr ffu foa fob fof foo for fou fra frb frd frf fro frr fru fua fub fud fuf fuo fur fuu oaa oab oad oaf oao oar oau ob- oba obb obd obf obo obr obu oda odb odd odf odo odr odu of- ofa ofb ofd off ofo ofr ofu oo- ooa oob ood oof ooo oor or- ora orb ord orf oro orr oru ou- oua oud ouf ouo our ra- raa rab rad raf rao rar rau rba rbb rbd rbf rbo rbr rbu rda rdb rdd rdf rdo rdr rdu rfa rfb rfd rff rfo rfr rfu roa rob rod rof roo ror rou rra rrb rrd rrf rrr rru rua rub rud ruf ruo rur ruu ua- uaa uab uad uaf uao uar uau uba ubb ubf ubo ubr ubu uda udb udd udf udo udr udu ufa ufd uff ufo ufr ufu uoa uob uod uoo uor ur- ura urb urd urf uro urr uru uua uur uuu