-er a-a a-b a-c a-t aaa aab aac aae aak aan aao aar aat ab- aba abb abc abe abk abn abo abr abt ac- aca acb acc ace ack acn aco acr act aea aeb aec aee aek aen aeo aer aet aka akb akc ake akk akn ako akr an- ana anb anc ane ank ann ano anr ant aoa aob aoc aoe aok aon aoo aor aot ar- ara arb arc are ark arn aro arr art at- ata atb atc ate atn ato atr att baa bab bac bae bak ban bao bar bat bba bbb bbc bbe bbk bbn bbo bbr bbt bca bcb bcc bce bck bcn bco bcr bct be- bea beb bec bee bek ben beo ber bet bka bkb bkc bke bkk bkn bko bkr bkt bna bnb bnc bne bnk bnn bno bnr bnt boa bob boc boe bok bon boo bor bot bra brb bre brk brn bro brr brt bta btb btc bte btk btn bto btr btt c-- caa cab cac cae cak can cao car cat cba cbb cbc cbe cbk cbn cbo cbr cbt cca ccb ccc cce cck ccn cco ccr cct ce- cea ceb cec cee cek cen ceo cer cet cka ckb ckc cko ckt cn- cna cnb cnc cne cnn cno cnr cnt co- coa cob coc coe cok con coo cor cot cra crb crc cre crk crn cro crr crt cta ctb ctc cte ctk ctn cto ctr ctt eaa eab eac eae eak ean eao ear eat eba ebb ebc ebe ebk ebn ebo ebr ebt ec- eca ecb ecc ece eck ecn eco ecr ect eea eeb eec eee eek een eeo eer eet eka ekb ekc eke eko ekr ekt en- ena enb enc ene enk enn eno enr ent eo- eoa eob eoc eoe eok eon eoo eor eot era erb erc ere erk ern ero err ert eta etb etc ete etk etn eto etr ett k-t ka- kaa kab kac kae kak kan kao kar kat kba kbb kbc kbe kbk kbn kbo kbr kca kcb kcc kce kck kcn kcr kct ke- kea keb kec kee kek ken keo ker ket kkb kkc kke kkk kkn kkr kkt kn- kna knc kne knk knn kno knr knt koa kob koc koe kok kon koo kor kot kra krc krk krn kro krr krt kta ktb ktc kte ktk ktn kto ktr ktt naa nab nac nae nak nan nao nar nat nba nbb nbc nbe nbk nbn nbo nbr nbt nca ncb ncc nce nck ncn nco ncr nct ne- nea neb nec nee nek nen neo ner net nka nkc nke nkk nkn nko nkr nkt nna nnb nnc nne nnk nnn nno nnt no- noa nob noc noe nok non noo nor not nra nrb nrc nre nrk nrn nro nrr nrt nta ntb ntc nte ntk ntn nto ntr ntt oaa oab oac oae oak oan oao oar oat ob- oba obb obc obe obk obn obo obr obt oc- oca ocb occ ock ocn oco ocr oct oea oeb oec oee oen oeo oer oet oka okb okc oke okk oko okr on- ona onb onc one onk onn ono onr ont oo- ooa oob ooc ook oon ooo oor oot or- ora orb orc ore ork orn oro orr ort ot- ota otb otc ote otk otn oto otr ott ra- raa rab rac rae rak ran rao rar rat rba rbb rbc rbe rbk rbn rbo rbr rbt rca rcb rcc rce rcn rco rcr rct re- rea reb rec ree rek ren reo rer ret rkb rkc rke rkk rko rkt rna rnb rnc rnn rno rnr rnt roa rob roc roe rok ron roo ror rot rra rrb rrc rrk rrn rrr rrt rta rtb rtc rte rtk rtn rto rtr rtt taa tab tac tae tak tan tao tar tat tba tbb tbc tbe tbk tbn tbo tbr tbt tca tcb tcc tce tck tcn tco tcr tct te- tea teb tec tee tek ten teo ter tet tka tkb tkc tke tkk tko tkr tkt tna tnb tnc tne tnk tnn tno tnr tnt to- toa tob toc toe tok ton too tor tot tra trb trc tre trk trn tro trr trt tta ttb ttc tte ttk ttn tto ttr ttt