a-a a-b a-i aaa aab aag aai aar aas ab- aba abb abg abi abr abs ag- aga agb agg agi agr ags ai- aia aib aig aii air ais ar- ara arb arg ari arr ars as- asa asb asg asi asr ass baa bab bag bai bar bas bba bbb bbg bbi bbr bbs bga bgb bgg bgi bgr bgs bi- bia bib big bii bir bis bra brb brg bri brr brs bsa bsb bsg bsi bsr bss gaa gab gag gai gar gas gba gbg gbi gbr gbs gga ggb ggg ggi ggr ggs gia gib gig gii gir gis gra grb grg gri grr grs gsa gsb gsg gsi gsr gss ia- iaa iab iag iai iar ias iba ibb ibg ibi ibr ibs iga igb igg igi igr igs iia iib iii iir iis ir- ira irb irg iri irr irs is- isa isb isg isi isr iss ra- raa rab rag rai rar ras rba rbb rbg rbi rbr rbs rga rgb rgg rgi rgr rgs ria rib rig rii rir ris rra rrb rrg rri rrr rrs rsa rsb rsg rsi rsr rss saa sab sag sai sar sas sba sbb sbg sbi sbr sbs sga sgb sgg sgi sgr sgs sia sib sig sii sir sis sr- sra srb srg sri srr srs ss- ssa ssb ssg ssi ssr sss