a-a a-b aaa aab aag aao aar aau ab- aba abb abg abo abr abu ag- aga agb agg ago agr agu aoa aob aog aoo aor aou ar- ara arb arg aro arr aru au- aua aub aug auo aur b-u baa bab bag bao bar bau bba bbb bbg bbo bbr bbu bga bgb bgg bgo bgr bgu boa bob bog boo bor bou bra brb brg bro brr bru bua bub bug buo bur buu gaa gab gag gao gar gau gba gbg gbo gbr gbu gga ggb ggg ggo ggr ggu goa gob gog goo gor gou gra grb grg gro grr gru gu- gua gub gug guo gur guu oaa oab oag oao oar oau ob- oba obb obg obo obr obu oga ogg ogo oo- ooa oob oog ooo oor or- ora orb org oro orr oru ou- oua ouo our ra- raa rab rag rao rar rau rba rbb rbg rbo rbr rbu rga rgb rgg rgo rgr roa rob rog roo ror rou rra rrb rrg rrr rru rua rub rug ruo rur ruu ua- uaa uab uag uao uar uau uba ubb ubg ubo ubr ubu uga ugb ugg ugo ugr ugu uoa uob uog uoo uor ur- ura urb urg uro urr uru uua uug uur uuu