a-a a-b a-c a-t aaa aab aac aaf aak aan aao aar aat ab- aba abb abc abf abk abn abo abr abt ac- aca acb acc acf ack acn aco acr act af- afa afb afc aff afk afn afo afr aft aka akb akc akk akn ako akr an- ana anb anc anf ank ann ano anr ant aoa aob aoc aof aok aon aoo aor aot ar- ara arb arc arf ark arn aro arr art at- ata atb atc atf atn ato atr att baa bab bac baf bak ban bao bar bat bba bbb bbc bbf bbk bbn bbo bbr bbt bca bcb bcc bcf bck bcn bco bcr bct bfa bfb bfc bff bfn bfo bfr bft bka bkb bkc bkf bkk bkn bko bkr bkt bna bnb bnc bnf bnk bnn bno bnr bnt boa bob boc bof bok bon boo bor bot bra brb brf brk brn bro brr brt bta btb btc btf btk btn bto btr btt c-- caa cab cac caf cak can cao car cat cba cbb cbc cbf cbk cbn cbo cbr cbt cca ccb ccc ccf cck ccn cco ccr cct cfa cfb cfc cff cfk cfn cfo cfr cft cka ckb ckc cko ckt cn- cna cnb cnc cnf cnn cno cnr cnt co- coa cob coc cof cok con coo cor cot cra crb crc crf crk crn cro crr crt cta ctb ctc ctf ctk ctn cto ctr ctt faa fab fac faf fak fan fao far fat fba fbb fbc fbf fbk fbn fbo fbr fbt fca fcb fcc fcf fck fcn fco fcr fct ffa ffc fff ffk ffn ffo ffr fft fka fkb fkc fkf fkk fkt fna fnb fnc fnf fnk fnn fnr fnt foa fob foc fof fok fon foo for fot fra frb frc frf frk frn fro frr frt fta ftb ftc ftf ftk ftn fto ftr ftt k-t ka- kaa kab kac kaf kak kan kao kar kat kba kbb kbc kbf kbk kbn kbo kbr kca kcb kcc kck kcn kcr kct kfa kfc kff kfo kkb kkc kkk kkn kkr kkt kn- kna knc knf knk knn kno knr knt koa kob koc kof kok kon koo kor kot kra krc krf krk krn kro krr krt kta ktb ktc ktf ktk ktn kto ktr ktt naa nab nac naf nak nan nao nar nat nba nbb nbc nbf nbk nbn nbo nbr nbt nca ncb ncc ncf nck ncn nco ncr nct nfa nfb nfc nff nfk nfn nfo nfr nft nka nkc nkf nkk nkn nko nkr nkt nna nnb nnc nnf nnk nnn nno nnt no- noa nob noc nof nok non noo nor not nra nrb nrc nrf nrk nrn nro nrr nrt nta ntb ntc ntf ntk ntn nto ntr ntt oaa oab oac oaf oak oan oao oar oat ob- oba obb obc obf obk obn obo obr obt oc- oca ocb occ ocf ock ocn oco ocr oct of- ofa ofb ofc off ofn ofo ofr oft oka okb okc okk oko okr on- ona onb onc onf onk onn ono onr ont oo- ooa oob ooc oof ook oon ooo oor oot or- ora orb orc orf ork orn oro orr ort ot- ota otb otc otf otk otn oto otr ott ra- raa rab rac raf rak ran rao rar rat rba rbb rbc rbf rbk rbn rbo rbr rbt rca rcb rcc rcf rcn rco rcr rct rfa rfb rfc rff rfk rfn rfo rfr rft rkb rkc rkf rkk rko rkt rna rnb rnc rnn rno rnr rnt roa rob roc rof rok ron roo ror rot rra rrb rrc rrf rrk rrn rrr rrt rta rtb rtc rtf rtk rtn rto rtr rtt taa tab tac taf tak tan tao tar tat tba tbb tbc tbf tbk tbn tbo tbr tbt tca tcb tcc tcf tck tcn tco tcr tct tfa tfb tfc tff tfk tfn tfo tfr tft tka tkb tkc tkk tko tkr tkt tna tnb tnc tnf tnk tnn tno tnr tnt to- toa tob toc tof tok ton too tor tot tra trb trc trf trk trn tro trr trt tta ttb ttc ttf ttk ttn tto ttr ttt