a-a a-b a-i aaa aab aag aai aao aas ab- aba abb abg abi abo abs ag- aga agb agg agi ago ags ai- aia aib aig aii aio ais aoa aob aog aoi aoo aos as- asa asb asg asi aso ass baa bab bag bai bao bas bba bbb bbg bbi bbo bbs bga bgb bgg bgi bgo bgs bi- bia bib big bii bio bis boa bob bog boi boo bos bsa bsb bsg bsi bso bss gaa gab gag gai gao gas gba gbg gbi gbo gbs gga ggb ggg ggi ggo ggs gia gib gig gii gio gis goa gob gog goi goo gos gsa gsb gsg gsi gso gss ia- iaa iab iag iai iao ias iba ibb ibg ibi ibo ibs iga igb igg igi igo igs iia iib iii iio iis io- ioa iob iog ioi ioo ios is- isa isb isg isi iso iss o-i oaa oab oag oai oao oas ob- oba obb obg obi obo obs oga ogg ogi ogo ogs oia oib oii oio ois oo- ooa oob oog ooi ooo oos os- osa osb osg osi oso oss saa sab sag sai sao sas sba sbb sbg sbi sbo sbs sga sgb sgg sgi sgo sgs sia sib sig sii sio sis soa sob sog soi soo sos ss- ssa ssb ssg ssi sso sss