a-a a-b a-c a-t aaa aab aac aak aar aas aat ab- aba abb abc abk abr abs abt ac- aca acb acc ack acr acs act aka akb akc akk akr aks ar- ara arb arc ark arr ars art as- asa asb asc ask asr ass ast at- ata atb atc atr ats att baa bab bac bak bar bas bat bba bbb bbc bbk bbr bbs bbt bca bcb bcc bck bcr bcs bct bka bkb bkc bkk bkr bks bkt bra brb brk brr brs brt bsa bsb bsc bsk bsr bss bst bta btb btc btk btr bts btt c-- caa cab cac cak car cas cat cba cbb cbc cbk cbr cbs cbt cca ccb ccc cck ccr ccs cct cka ckb ckc cks ckt cra crb crc crk crr crs crt csa csb csc csk csr css cst cta ctb ctc ctk ctr cts ctt k-t ka- kaa kab kac kak kar kas kat kba kbb kbc kbk kbr kbs kca kcb kcc kck kcr kcs kct kkb kkc kkk kkr kks kkt kra krc krk krr krs krt ksa ksb ksc ksk ksr kss kst kta ktb ktc ktk ktr kts ktt ra- raa rab rac rak rar ras rat rba rbb rbc rbk rbr rbs rbt rca rcb rcc rcr rcs rct rkb rkc rkk rks rkt rra rrb rrc rrk rrr rrs rrt rsa rsb rsc rsk rsr rss rst rta rtb rtc rtk rtr rts rtt saa sab sac sak sar sas sat sba sbb sbc sbk sbr sbs sbt sca scb scc sck scr scs sct sk- ska skb skc skk skr sks skt sr- sra srb src srk srr srs srt ss- ssa ssb ssc ssk ssr sss sst sta stb stc stk str sts stt taa tab tac tak tar tas tat tba tbb tbc tbk tbr tbs tbt tca tcb tcc tck tcr tcs tct tka tkb tkc tkk tkr tks tkt tra trb trc trk trr trs trt tsa tsb tsc tsk tsr tss tst tta ttb ttc ttk ttr tts ttt