a-a a-b a-c aaa aab aac aad aak aan aao aas ab- aba abb abc abd abk abn abo abs ac- aca acb acc acd ack acn aco acs ad- ada adb adc add adk adn ado ads aka akb akc akd akk akn ako aks an- ana anb anc and ank ann ano ans aoa aob aoc aod aok aon aoo aos as- asa asb asc asd ask asn aso ass baa bab bac bad bak ban bao bas bba bbb bbc bbd bbk bbn bbo bbs bca bcb bcc bcd bck bcn bco bcs bda bdb bdc bdd bdk bdo bds bka bkb bkc bkk bkn bko bks bna bnb bnc bnd bnk bnn bno bns boa bob boc bod bok bon boo bos bsa bsb bsc bsd bsk bsn bso bss c-- caa cab cac cad cak can cao cas cba cbb cbc cbd cbk cbn cbo cbs cca ccb ccc ccd cck ccn cco ccs cda cdb cdc cdd cdk cdn cdo cds cka ckb ckc ckd cko cks cn- cna cnb cnc cnd cnn cno cns co- coa cob coc cod cok con coo cos csa csb csc csd csk csn cso css daa dab dac dad dak dan dao das dba dbb dbc dbd dbk dbn dbo dbs dca dcb dcc dcd dck dcn dco dcs dda ddb ddc ddd ddk ddn ddo dds dka dkb dkc dkk dko dks dna dnb dnc dnd dnk dnn dno dns doa dob doc dod dok don doo dos dsa dsb dsc dsd dsk dsn dso dss ka- kaa kab kac kad kak kan kao kas kba kbb kbc kbd kbk kbn kbo kbs kca kcb kcc kcd kck kcn kcs kda kdb kdc kdk kdo kds kkb kkc kkk kkn kks kn- kna knc knd knk knn kno koa kob koc kod kok kon koo kos ksa ksb ksc ksd ksk ksn kso kss naa nab nac nad nak nan nao nas nba nbb nbc nbd nbk nbn nbo nbs nca ncb ncc ncd nck ncn nco ncs nda ndb ndc ndd ndk ndn ndo nds nka nkc nkk nkn nko nks nna nnb nnc nnk nnn nno nns no- noa nob noc nod nok non noo nos nsa nsb nsc nsd nsk nsn nso nss oaa oab oac oad oak oan oao oas ob- oba obb obc obd obk obn obo obs oc- oca ocb occ ocd ock ocn oco ocs oda odb odc odd odn odo ods oka okb okc okd okk oko oks on- ona onb onc ond onk onn ono ons oo- ooa oob ooc ood ook oon ooo oos os- osa osb osc osd osk osn oso oss saa sab sac sad sak san sao sas sba sbb sbc sbd sbk sbn sbo sbs sca scb scc scd sck scn sco scs sda sdb sdc sdd sdk sdn sdo sds sk- ska skb skc skd skk sko sks sna snb snc snd snk snn sno sns soa sob soc sod sok son soo sos ss- ssa ssb ssc ssd ssk ssn sso sss