a-a a-b aaa aab aag aah aao aar ab- aba abb abg abh abo abr ag- aga agb agg agh ago agr aha ahb ahg ahh aho ahr aoa aob aog aoh aoo aor ar- ara arb arg arh aro arr baa bab bag bah bao bar bba bbb bbg bbh bbo bbr bga bgb bgg bgh bgo bgr bha bhb bhg bhh bho bhr boa bob bog boh boo bor bra brb brg brh bro brr gaa gab gag gah gao gar gba gbg gbh gbo gbr gga ggb ggg ggh ggo ggr gha ghb ghg ghh gho ghr goa gob gog goh goo gor gra grb grg grh gro grr haa hab hag hah hao har hba hbb hbg hbh hbo hbr hga hgb hgg hgh hgo hgr hha hhb hhg hhh hho hhr hoa hob hog hoh hoo hor hr- hra hrb hrg hrh hro hrr oaa oab oag oah oao oar ob- oba obb obg obh obo obr oga ogg ogh ogo oha ohg ohh oho ohr oo- ooa oob oog ooh ooo oor or- ora orb org orh oro orr ra- raa rab rag rah rao rar rba rbb rbg rbh rbo rbr rga rgb rgg rgh rgo rgr rh- rha rhb rhg rhh rho rhr roa rob rog roh roo ror rra rrb rrg rrh rrr