a-a a-b a-c a-t aaa aab aac aae aak aas aat aax ab- aba abb abc abe abk abs abt abx ac- aca acb acc ace ack acs act acx aea aeb aec aee aek aes aet aex aka akb akc ake akk aks as- asa asb asc ase ask ass ast asx at- ata atb atc ate ats att atx ax- axa axe axk axs axt axx baa bab bac bae bak bas bat bax bba bbb bbc bbe bbk bbs bbt bbx bca bcb bcc bce bck bcs bct bcx be- bea beb bec bee bek bes bet bex bka bkb bkc bke bkk bks bkt bkx bsa bsb bsc bse bsk bss bst bsx bta btb btc bte btk bts btt btx bxb bxx c-- caa cab cac cae cak cas cat cax cba cbb cbc cbe cbk cbs cbt cbx cca ccb ccc cce cck ccs cct ccx ce- cea ceb cec cee cek ces cet cex cka ckb ckc cks ckt ckx csa csb csc cse csk css cst csx cta ctb ctc cte ctk cts ctt ctx cxc cxk cxs cxt cxx eaa eab eac eae eak eas eat eax eba ebb ebc ebe ebk ebs ebt ebx ec- eca ecb ecc ece eck ecs ect ecx eea eeb eec eee eek ees eet eex eka ekb ekc eke eks ekt es- esa esb esc ese esk ess est esx eta etb etc ete etk ets ett etx ex- exa exc exe exs ext exx k-t ka- kaa kab kac kae kak kas kat kax kba kbb kbc kbe kbk kbs kbx kca kcb kcc kce kck kcs kct kcx ke- kea keb kec kee kek kes ket kex kkb kkc kke kkk kks kkt ksa ksb ksc kse ksk kss kst kta ktb ktc kte ktk kts ktt saa sab sac sae sak sas sat sax sba sbb sbc sbe sbk sbs sbt sbx sca scb scc sce sck scs sct scx se- sea seb sec see sek ses set sex sk- ska skb skc ske skk sks skt skx ss- ssa ssb ssc sse ssk sss sst ssx sta stb stc ste stk sts stt stx sxc sxs sxt t-x taa tab tac tae tak tas tat tax tba tbb tbc tbe tbk tbs tbt tca tcb tcc tce tck tcs tct tcx te- tea teb tec tee tek tes tet tex tka tkb tkc tke tkk tks tkt tsa tsb tsc tse tsk tss tst tsx tta ttb ttc tte ttk tts ttt ttx txe txk txs txt xaa xac xak xas xat xbc xbe xbx xcb xcx xee xes xet xex xkb xke xks xsa xsb xsc xss xst xtc xts xtx xxx