a-a a-b a-c aaa aab aac aad aak aan aas ab- aba abb abc abd abk abn abs ac- aca acb acc acd ack acn acs ad- ada adb adc add adk adn ads aka akb akc akd akk akn aks an- ana anb anc and ank ann ans as- asa asb asc asd ask asn ass baa bab bac bad bak ban bas bba bbb bbc bbd bbk bbn bbs bca bcb bcc bcd bck bcn bcs bda bdb bdc bdd bdk bds bka bkb bkc bkk bkn bks bna bnb bnc bnd bnk bnn bns bsa bsb bsc bsd bsk bsn bss c-- caa cab cac cad cak can cas cba cbb cbc cbd cbk cbn cbs cca ccb ccc ccd cck ccn ccs cda cdb cdc cdd cdk cdn cds cka ckb ckc ckd cks cn- cna cnb cnc cnd cnn cns csa csb csc csd csk csn css daa dab dac dad dak dan das dba dbb dbc dbd dbk dbn dbs dca dcb dcc dcd dck dcn dcs dda ddb ddc ddd ddk ddn dds dka dkb dkc dkk dks dna dnb dnc dnd dnk dnn dns dsa dsb dsc dsd dsk dsn dss ka- kaa kab kac kad kak kan kas kba kbb kbc kbd kbk kbn kbs kca kcb kcc kcd kck kcn kcs kda kdb kdc kdk kds kkb kkc kkk kkn kks kn- kna knc knd knk knn ksa ksb ksc ksd ksk ksn kss naa nab nac nad nak nan nas nba nbb nbc nbd nbk nbn nbs nca ncb ncc ncd nck ncn ncs nda ndb ndc ndd ndk ndn nds nka nkc nkk nkn nks nna nnb nnc nnk nnn nns nsa nsb nsc nsd nsk nsn nss saa sab sac sad sak san sas sba sbb sbc sbd sbk sbn sbs sca scb scc scd sck scn scs sda sdb sdc sdd sdk sdn sds sk- ska skb skc skd skk sks sna snb snc snd snk snn sns ss- ssa ssb ssc ssd ssk ssn sss