-er a-a a-b a-c a-t aaa aab aac aae aak aar aas aat aax ab- aba abb abc abe abk abr abs abt abx ac- aca acb acc ace ack acr acs act acx aea aeb aec aee aek aer aes aet aex aka akb akc ake akk akr aks ar- ara arb arc are ark arr ars art arx as- asa asb asc ase ask asr ass ast asx at- ata atb atc ate atr ats att atx ax- axa axe axk axr axs axt axx baa bab bac bae bak bar bas bat bax bba bbb bbc bbe bbk bbr bbs bbt bbx bca bcb bcc bce bck bcr bcs bct bcx be- bea beb bec bee bek ber bes bet bex bka bkb bkc bke bkk bkr bks bkt bkx bra brb bre brk brr brs brt brx bsa bsb bsc bse bsk bsr bss bst bsx bta btb btc bte btk btr bts btt btx bxb bxx c-- caa cab cac cae cak car cas cat cax cba cbb cbc cbe cbk cbr cbs cbt cbx cca ccb ccc cce cck ccr ccs cct ccx ce- cea ceb cec cee cek cer ces cet cex cka ckb ckc cks ckt ckx cra crb crc cre crk crr crs crt crx csa csb csc cse csk csr css cst csx cta ctb ctc cte ctk ctr cts ctt ctx cxc cxk cxr cxs cxt cxx eaa eab eac eae eak ear eas eat eax eba ebb ebc ebe ebk ebr ebs ebt ebx ec- eca ecb ecc ece eck ecr ecs ect ecx eea eeb eec eee eek eer ees eet eex eka ekb ekc eke ekr eks ekt era erb erc ere erk err ers ert es- esa esb esc ese esk esr ess est esx eta etb etc ete etk etr ets ett etx ex- exa exc exe exr exs ext exx k-t ka- kaa kab kac kae kak kar kas kat kax kba kbb kbc kbe kbk kbr kbs kbx kca kcb kcc kce kck kcr kcs kct kcx ke- kea keb kec kee kek ker kes ket kex kkb kkc kke kkk kkr kks kkt kra krc krk krr krs krt ksa ksb ksc kse ksk ksr kss kst kta ktb ktc kte ktk ktr kts ktt ra- raa rab rac rae rak rar ras rat rax rba rbb rbc rbe rbk rbr rbs rbt rbx rca rcb rcc rce rcr rcs rct rcx re- rea reb rec ree rek rer res ret rex rkb rkc rke rkk rks rkt rra rrb rrc rrk rrr rrs rrt rsa rsb rsc rse rsk rsr rss rst rsx rta rtb rtc rte rtk rtr rts rtt rtx rxr rxs saa sab sac sae sak sar sas sat sax sba sbb sbc sbe sbk sbr sbs sbt sbx sca scb scc sce sck scr scs sct scx se- sea seb sec see sek ser ses set sex sk- ska skb skc ske skk skr sks skt skx sr- sra srb src sre srk srr srs srt srx ss- ssa ssb ssc sse ssk ssr sss sst ssx sta stb stc ste stk str sts stt stx sxc sxs sxt t-x taa tab tac tae tak tar tas tat tax tba tbb tbc tbe tbk tbr tbs tbt tca tcb tcc tce tck tcr tcs tct tcx te- tea teb tec tee tek ter tes tet tex tka tkb tkc tke tkk tkr tks tkt tra trb trc tre trk trr trs trt trx tsa tsb tsc tse tsk tsr tss tst tsx tta ttb ttc tte ttk ttr tts ttt ttx txe txk txs txt xaa xac xak xar xas xat xbc xbe xbr xbx xcb xcr xcx xee xer xes xet xex xkb xke xks xrc xrt xrx xsa xsb xsc xss xst xtc xtr xts xtx xxx