a-a a-b a-c a-t aaa aab aac aak aan aar aat ab- aba abb abc abk abn abr abt ac- aca acb acc ack acn acr act aka akb akc akk akn akr an- ana anb anc ank ann anr ant ar- ara arb arc ark arn arr art at- ata atb atc atn atr att baa bab bac bak ban bar bat bba bbb bbc bbk bbn bbr bbt bca bcb bcc bck bcn bcr bct bka bkb bkc bkk bkn bkr bkt bna bnb bnc bnk bnn bnr bnt bra brb brk brn brr brt bta btb btc btk btn btr btt c-- caa cab cac cak can car cat cba cbb cbc cbk cbn cbr cbt cca ccb ccc cck ccn ccr cct cka ckb ckc ckt cn- cna cnb cnc cnn cnr cnt cra crb crc crk crn crr crt cta ctb ctc ctk ctn ctr ctt k-t ka- kaa kab kac kak kan kar kat kba kbb kbc kbk kbn kbr kca kcb kcc kck kcn kcr kct kkb kkc kkk kkn kkr kkt kn- kna knc knk knn knr knt kra krc krk krn krr krt kta ktb ktc ktk ktn ktr ktt naa nab nac nak nan nar nat nba nbb nbc nbk nbn nbr nbt nca ncb ncc nck ncn ncr nct nka nkc nkk nkn nkr nkt nna nnb nnc nnk nnn nnt nra nrb nrc nrk nrn nrr nrt nta ntb ntc ntk ntn ntr ntt ra- raa rab rac rak ran rar rat rba rbb rbc rbk rbn rbr rbt rca rcb rcc rcn rcr rct rkb rkc rkk rkt rna rnb rnc rnn rnr rnt rra rrb rrc rrk rrn rrr rrt rta rtb rtc rtk rtn rtr rtt taa tab tac tak tan tar tat tba tbb tbc tbk tbn tbr tbt tca tcb tcc tck tcn tcr tct tka tkb tkc tkk tkr tkt tna tnb tnc tnk tnn tnr tnt tra trb trc trk trn trr trt tta ttb ttc ttk ttn ttr ttt