a-a a-b a-i aaa aab aaf aag aai aar aas ab- aba abb abf abg abi abr abs af- afa afb aff afg afi afr afs ag- aga agb agf agg agi agr ags ai- aia aib aif aig aii air ais ar- ara arb arf arg ari arr ars as- asa asb asf asg asi asr ass baa bab baf bag bai bar bas bba bbb bbf bbg bbi bbr bbs bfa bfb bff bfg bfi bfr bfs bga bgb bgf bgg bgi bgr bgs bi- bia bib bif big bii bir bis bra brb brf brg bri brr brs bsa bsb bsf bsg bsi bsr bss faa fab faf fag fai far fas fba fbb fbf fbg fbi fbr fbs ffa fff ffg ffi ffr ffs fga fgb fgf fgg fgi fgr fgs fia fib fif fig fii fir fis fra frb frf frg fri frr frs fsa fsb fsf fsg fsi fsr fss gaa gab gaf gag gai gar gas gba gbf gbg gbi gbr gbs gfa gfb gff gfi gfr gfs gga ggb ggg ggi ggr ggs gia gib gif gig gii gir gis gra grb grf grg gri grr grs gsa gsb gsf gsg gsi gsr gss i-f ia- iaa iab iaf iag iai iar ias iba ibb ibf ibg ibi ibr ibs ifa ifb iff ifg ifi ifr ifs iga igb igf igg igi igr igs iia iib iif iii iir iis ir- ira irb irf irg iri irr irs is- isa isb isf isg isi isr iss ra- raa rab raf rag rai rar ras rba rbb rbf rbg rbi rbr rbs rfa rfb rff rfg rfi rfr rfs rga rgb rgf rgg rgi rgr rgs ria rib rif rig rii rir ris rra rrb rrf rrg rri rrr rrs rsa rsb rsf rsg rsi rsr rss saa sab saf sag sai sar sas sba sbb sbf sbg sbi sbr sbs sfa sfb sff sfg sfi sfr sfs sga sgb sgf sgg sgi sgr sgs sia sib sif sig sii sir sis sr- sra srb srf srg sri srr srs ss- ssa ssb ssf ssg ssi ssr sss