a-a a-b a-c a-t aaa aab aac aar aas aat aau ab- aba abb abc abr abs abt abu ac- aca acb acc acr acs act acu ar- ara arb arc arr ars art aru as- asa asb asc asr ass ast asu at- ata atb atc atr ats att atu au- aua aub auc aur aus aut b-u baa bab bac bar bas bat bau bba bbb bbc bbr bbs bbt bbu bca bcb bcc bcr bcs bct bcu bra brb brr brs brt bru bsa bsb bsc bsr bss bst bsu bta btb btc btr bts btt btu bua bub buc bur bus but buu c-- caa cab cac car cas cat cau cba cbb cbc cbr cbs cbt cbu cca ccb ccc ccr ccs cct ccu cra crb crc crr crs crt cru csa csb csc csr css cst csu cta ctb ctc ctr cts ctt ctu cua cub cuc cur cus cut cuu ra- raa rab rac rar ras rat rau rba rbb rbc rbr rbs rbt rbu rca rcb rcc rcr rcs rct rcu rra rrb rrc rrr rrs rrt rru rsa rsb rsc rsr rss rst rsu rta rtb rtc rtr rts rtt rtu rua rub ruc rur rus rut ruu saa sab sac sar sas sat sau sba sbb sbc sbr sbs sbt sbu sca scb scc scr scs sct scu sr- sra srb src srr srs srt ss- ssa ssb ssc ssr sss sst ssu sta stb stc str sts stt stu sua sub suc sur sus sut suu taa tab tac tar tas tat tau tba tbb tbc tbr tbs tbt tbu tca tcb tcc tcr tcs tct tcu tra trb trc trr trs trt tru tsa tsb tsc tsr tss tst tsu tta ttb ttc ttr tts ttt ttu tua tub tuc tur tus tut tuu ua- uaa uab uac uar uas uat uau uba ubb ubc ubr ubs ubt ubu uca ucb ucc ucr ucs uct ucu ur- ura urb urc urr urs urt uru usa usb usc usr uss ust usu uta utb utc utr uts utt utu uua uuc uur uus uut uuu