a-a a-b aaa aab aag aan aar aas ab- aba abb abg abn abr abs ag- aga agb agg agn agr ags an- ana anb ang ann anr ans ar- ara arb arg arn arr ars as- asa asb asg asn asr ass baa bab bag ban bar bas bba bbb bbg bbn bbr bbs bga bgb bgg bgn bgr bgs bna bnb bng bnn bnr bns bra brb brg brn brr brs bsa bsb bsg bsn bsr bss gaa gab gag gan gar gas gba gbg gbn gbr gbs gga ggb ggg ggn ggr ggs gna gnb gnn gnr gns gra grb grg grn grr grs gsa gsb gsg gsn gsr gss naa nab nag nan nar nas nba nbb nbg nbn nbr nbs nga ngb ngg ngn ngs nna nnb nng nnn nns nra nrb nrg nrn nrr nrs nsa nsb nsg nsn nsr nss ra- raa rab rag ran rar ras rba rbb rbg rbn rbr rbs rga rgb rgg rgn rgr rgs rna rnb rng rnn rnr rns rra rrb rrg rrn rrr rrs rsa rsb rsg rsn rsr rss saa sab sag san sar sas sba sbb sbg sbn sbr sbs sga sgb sgg sgn sgr sgs sna snb sng snn snr sns sr- sra srb srg srn srr srs ss- ssa ssb ssg ssn ssr sss