a-a a-b a-c a-t aaa aab aac aan aao aar aat ab- aba abb abc abn abo abr abt ac- aca acb acc acn aco acr act an- ana anb anc ann ano anr ant aoa aob aoc aon aoo aor aot ar- ara arb arc arn aro arr art at- ata atb atc atn ato atr att baa bab bac ban bao bar bat bba bbb bbc bbn bbo bbr bbt bca bcb bcc bcn bco bcr bct bna bnb bnc bnn bno bnr bnt boa bob boc bon boo bor bot bra brb brn bro brr brt bta btb btc btn bto btr btt c-- caa cab cac can cao car cat cba cbb cbc cbn cbo cbr cbt cca ccb ccc ccn cco ccr cct cn- cna cnb cnc cnn cno cnr cnt co- coa cob coc con coo cor cot cra crb crc crn cro crr crt cta ctb ctc ctn cto ctr ctt naa nab nac nan nao nar nat nba nbb nbc nbn nbo nbr nbt nca ncb ncc ncn nco ncr nct nna nnb nnc nnn nno nnt no- noa nob noc non noo nor not nra nrb nrc nrn nro nrr nrt nta ntb ntc ntn nto ntr ntt oaa oab oac oan oao oar oat ob- oba obb obc obn obo obr obt oc- oca ocb occ ocn oco ocr oct on- ona onb onc onn ono onr ont oo- ooa oob ooc oon ooo oor oot or- ora orb orc orn oro orr ort ot- ota otb otc otn oto otr ott ra- raa rab rac ran rao rar rat rba rbb rbc rbn rbo rbr rbt rca rcb rcc rcn rco rcr rct rna rnb rnc rnn rno rnr rnt roa rob roc ron roo ror rot rra rrb rrc rrn rrr rrt rta rtb rtc rtn rto rtr rtt taa tab tac tan tao tar tat tba tbb tbc tbn tbo tbr tbt tca tcb tcc tcn tco tcr tct tna tnb tnc tnn tno tnr tnt to- toa tob toc ton too tor tot tra trb trc trn tro trr trt tta ttb ttc ttn tto ttr ttt