a-a a-b a-c a-t aaa aab aac aan aao aar aat aax ab- aba abb abc abn abo abr abt abx ac- aca acb acc acn aco acr act acx an- ana anb anc ann ano anr ant anx aoa aob aoc aon aoo aor aot aox ar- ara arb arc arn aro arr art arx at- ata atb atc atn ato atr att atx ax- axa axn axo axr axt axx baa bab bac ban bao bar bat bax bba bbb bbc bbn bbo bbr bbt bbx bca bcb bcc bcn bco bcr bct bcx bna bnb bnc bnn bno bnr bnt bnx boa bob boc bon boo bor bot box bra brb brn bro brr brt brx bta btb btc btn bto btr btt btx bxb bxn bxo bxx c-- caa cab cac can cao car cat cax cba cbb cbc cbn cbo cbr cbt cbx cca ccb ccc ccn cco ccr cct ccx cn- cna cnb cnc cnn cno cnr cnt cnx co- coa cob coc con coo cor cot cox cra crb crc crn cro crr crt crx cta ctb ctc ctn cto ctr ctt ctx cxc cxo cxr cxt cxx naa nab nac nan nao nar nat nax nba nbb nbc nbn nbo nbr nbt nbx nca ncb ncc ncn nco ncr nct ncx nna nnb nnc nnn nno nnt no- noa nob noc non noo nor not nox nra nrb nrc nrn nro nrr nrt nrx nta ntb ntc ntn nto ntr ntt ntx nxc nxt oaa oab oac oan oao oar oat oax ob- oba obb obc obn obo obr obt obx oc- oca ocb occ ocn oco ocr oct ocx on- ona onb onc onn ono onr ont onx oo- ooa oob ooc oon ooo oor oot oox or- ora orb orc orn oro orr ort orx ot- ota otb otc otn oto otr ott ox- oxa oxb oxc oxn oxo oxt oxx ra- raa rab rac ran rao rar rat rax rba rbb rbc rbn rbo rbr rbt rbx rca rcb rcc rcn rco rcr rct rcx rna rnb rnc rnn rno rnr rnt roa rob roc ron roo ror rot rox rra rrb rrc rrn rrr rrt rta rtb rtc rtn rto rtr rtt rtx rxr t-x taa tab tac tan tao tar tat tax tba tbb tbc tbn tbo tbr tbt tca tcb tcc tcn tco tcr tct tcx tna tnb tnc tnn tno tnr tnt tnx to- toa tob toc ton too tor tot tox tra trb trc trn tro trr trt trx tta ttb ttc ttn tto ttr ttt ttx txn txt xaa xac xan xar xat xbc xbr xbx xcb xcr xcx xna xnc xno xoa xoc xon xoo xor xot xox xrc xrt xrx xtc xtr xtx xxo xxx