a-a a-b a-c aaa aab aac aak aam aao aas ab- aba abb abc abk abm abo abs ac- aca acb acc ack acm aco acs aka akb akc akk akm ako aks ama amb amc amk amm amo ams aoa aob aoc aok aom aoo aos as- asa asb asc ask asm aso ass baa bab bac bak bam bao bas bba bbb bbc bbk bbm bbo bbs bca bcb bcc bck bcm bco bcs bka bkb bkc bkk bkm bko bks bma bmb bmc bmk bmm bmo bms boa bob boc bok bom boo bos bsa bsb bsc bsk bsm bso bss c-- caa cab cac cak cam cao cas cba cbb cbc cbk cbm cbo cbs cca ccb ccc cck ccm cco ccs cka ckb ckc ckm cko cks cma cmb cmc cmk cmm cmo cms co- coa cob coc cok com coo cos csa csb csc csk csm cso css ka- kaa kab kac kak kam kao kas kba kbb kbc kbk kbm kbo kbs kca kcb kcc kck kcm kcs kkb kkc kkk kkm kks kma kmb kmc kmk kmm kmo kms koa kob koc kok kom koo kos ksa ksb ksc ksk ksm kso kss m-o maa mab mac mak mam mao mas mba mbb mbc mbk mbm mbo mbs mc- mca mcb mcc mck mcm mco mcs mka mkb mkc mkk mkm mko mks mma mmb mmc mmk mmm mmo mms moa mob moc mok mom moo mos msa msb msc msk msm mso mss oaa oab oac oak oam oao oas ob- oba obb obc obk obm obo obs oc- oca ocb occ ock ocm oco ocs oka okb okc okk oko oks om- oma omb omc omm omo oms oo- ooa oob ooc ook oom ooo oos os- osa osb osc osk osm oso oss saa sab sac sak sam sao sas sba sbb sbc sbk sbm sbo sbs sca scb scc sck scm sco scs sk- ska skb skc skk skm sko sks sma smb smc smk smm smo sms soa sob soc sok som soo sos ss- ssa ssb ssc ssk ssm sso sss