a-a a-b a-c aaa aab aac aak aas aav ab- aba abb abc abk abs abv ac- aca acb acc ack acs acv aka akb akc akk aks akv as- asa asb asc ask ass asv av- ava avb avc avk avs baa bab bac bak bas bav bba bbb bbc bbk bbs bca bcb bcc bck bcs bcv bka bkb bkc bkk bks bkv bsa bsb bsc bsk bss bsv bva bvb bvc bvk bvs bvv c-- caa cab cac cak cas cav cba cbb cbc cbk cbs cbv cca ccb ccc cck ccs ccv cka ckb ckc cks csa csb csc csk css csv cva cvb cvc cvk cvs cvv ka- kaa kab kac kak kas kav kba kbb kbc kbk kbs kca kcb kcc kck kcs kkb kkc kkk kks kkv ksa ksb ksc ksk kss ksv kva kvb kvk kvs kvv saa sab sac sak sas sav sba sbb sbc sbk sbs sbv sca scb scc sck scs scv sk- ska skb skc skk sks ss- ssa ssb ssc ssk sss ssv sva svb svc svk svs svv v-a vaa vab vac vak vas vav vba vbc vbk vbs vbv vca vcc vcs vka vkb vsa vsb vsc vsk vss vsv vva vvb vvc vvs vvv