a-a a-b aaa aab aag aan aao aar ab- aba abb abg abn abo abr ag- aga agb agg agn ago agr an- ana anb ang ann ano anr aoa aob aog aon aoo aor ar- ara arb arg arn aro arr baa bab bag ban bao bar bba bbb bbg bbn bbo bbr bga bgb bgg bgn bgo bgr bna bnb bng bnn bno bnr boa bob bog bon boo bor bra brb brg brn bro brr gaa gab gag gan gao gar gba gbg gbn gbo gbr gga ggb ggg ggn ggo ggr gna gnb gnn gno gnr goa gob gog gon goo gor gra grb grg grn gro grr naa nab nag nan nao nar nba nbb nbg nbn nbo nbr nga ngb ngg ngn ngo nna nnb nng nnn nno no- noa nob nog non noo nor nra nrb nrg nrn nro nrr oaa oab oag oan oao oar ob- oba obb obg obn obo obr oga ogg ogn ogo on- ona onb ong onn ono onr oo- ooa oob oog oon ooo oor or- ora orb org orn oro orr ra- raa rab rag ran rao rar rba rbb rbg rbn rbo rbr rga rgb rgg rgn rgo rgr rna rnb rng rnn rno rnr roa rob rog ron roo ror rra rrb rrg rrn rrr