a-a a-b aaa aab aag aan aao aas ab- aba abb abg abn abo abs ag- aga agb agg agn ago ags an- ana anb ang ann ano ans aoa aob aog aon aoo aos as- asa asb asg asn aso ass baa bab bag ban bao bas bba bbb bbg bbn bbo bbs bga bgb bgg bgn bgo bgs bna bnb bng bnn bno bns boa bob bog bon boo bos bsa bsb bsg bsn bso bss gaa gab gag gan gao gas gba gbg gbn gbo gbs gga ggb ggg ggn ggo ggs gna gnb gnn gno gns goa gob gog gon goo gos gsa gsb gsg gsn gso gss naa nab nag nan nao nas nba nbb nbg nbn nbo nbs nga ngb ngg ngn ngo ngs nna nnb nng nnn nno nns no- noa nob nog non noo nos nsa nsb nsg nsn nso nss oaa oab oag oan oao oas ob- oba obb obg obn obo obs oga ogg ogn ogo ogs on- ona onb ong onn ono ons oo- ooa oob oog oon ooo oos os- osa osb osg osn oso oss saa sab sag san sao sas sba sbb sbg sbn sbo sbs sga sgb sgg sgn sgo sgs sna snb sng snn sno sns soa sob sog son soo sos ss- ssa ssb ssg ssn sso sss