a-a a-b a-c aaa aab aac aag aan aao aas ab- aba abb abc abg abn abo abs ac- aca acb acc acg acn aco acs ag- aga agb agc agg agn ago ags an- ana anb anc ang ann ano ans aoa aob aoc aog aon aoo aos as- asa asb asc asg asn aso ass baa bab bac bag ban bao bas bba bbb bbc bbg bbn bbo bbs bca bcb bcc bcg bcn bco bcs bga bgb bgc bgg bgn bgo bgs bna bnb bnc bng bnn bno bns boa bob boc bog bon boo bos bsa bsb bsc bsg bsn bso bss c-- caa cab cac cag can cao cas cba cbb cbc cbg cbn cbo cbs cca ccb ccc ccg ccn cco ccs cga cgb cgc cgg cgn cgo cgs cn- cna cnb cnc cng cnn cno cns co- coa cob coc cog con coo cos csa csb csc csg csn cso css gaa gab gac gag gan gao gas gba gbc gbg gbn gbo gbs gca gcb gcc gcg gcn gco gcs gga ggb ggc ggg ggn ggo ggs gna gnb gnc gnn gno gns goa gob goc gog gon goo gos gsa gsb gsc gsg gsn gso gss naa nab nac nag nan nao nas nba nbb nbc nbg nbn nbo nbs nca ncb ncc ncg ncn nco ncs nga ngb ngc ngg ngn ngo ngs nna nnb nnc nng nnn nno nns no- noa nob noc nog non noo nos nsa nsb nsc nsg nsn nso nss oaa oab oac oag oan oao oas ob- oba obb obc obg obn obo obs oc- oca ocb occ ocg ocn oco ocs oga ogc ogg ogn ogo ogs on- ona onb onc ong onn ono ons oo- ooa oob ooc oog oon ooo oos os- osa osb osc osg osn oso oss saa sab sac sag san sao sas sba sbb sbc sbg sbn sbo sbs sca scb scc scg scn sco scs sga sgb sgc sgg sgn sgo sgs sna snb snc sng snn sno sns soa sob soc sog son soo sos ss- ssa ssb ssc ssg ssn sso sss