-er a-a a-b a-c a-t aaa aab aac aae aan aao aar aat ab- aba abb abc abe abn abo abr abt ac- aca acb acc ace acn aco acr act aea aeb aec aee aen aeo aer aet an- ana anb anc ane ann ano anr ant aoa aob aoc aoe aon aoo aor aot ar- ara arb arc are arn aro arr art at- ata atb atc ate atn ato atr att baa bab bac bae ban bao bar bat bba bbb bbc bbe bbn bbo bbr bbt bca bcb bcc bce bcn bco bcr bct be- bea beb bec bee ben beo ber bet bna bnb bnc bne bnn bno bnr bnt boa bob boc boe bon boo bor bot bra brb bre brn bro brr brt bta btb btc bte btn bto btr btt c-- caa cab cac cae can cao car cat cba cbb cbc cbe cbn cbo cbr cbt cca ccb ccc cce ccn cco ccr cct ce- cea ceb cec cee cen ceo cer cet cn- cna cnb cnc cne cnn cno cnr cnt co- coa cob coc coe con coo cor cot cra crb crc cre crn cro crr crt cta ctb ctc cte ctn cto ctr ctt eaa eab eac eae ean eao ear eat eba ebb ebc ebe ebn ebo ebr ebt ec- eca ecb ecc ece ecn eco ecr ect eea eeb eec eee een eeo eer eet en- ena enb enc ene enn eno enr ent eo- eoa eob eoc eoe eon eoo eor eot era erb erc ere ern ero err ert eta etb etc ete etn eto etr ett naa nab nac nae nan nao nar nat nba nbb nbc nbe nbn nbo nbr nbt nca ncb ncc nce ncn nco ncr nct ne- nea neb nec nee nen neo ner net nna nnb nnc nne nnn nno nnt no- noa nob noc noe non noo nor not nra nrb nrc nre nrn nro nrr nrt nta ntb ntc nte ntn nto ntr ntt oaa oab oac oae oan oao oar oat ob- oba obb obc obe obn obo obr obt oc- oca ocb occ ocn oco ocr oct oea oeb oec oee oen oeo oer oet on- ona onb onc one onn ono onr ont oo- ooa oob ooc oon ooo oor oot or- ora orb orc ore orn oro orr ort ot- ota otb otc ote otn oto otr ott ra- raa rab rac rae ran rao rar rat rba rbb rbc rbe rbn rbo rbr rbt rca rcb rcc rce rcn rco rcr rct re- rea reb rec ree ren reo rer ret rna rnb rnc rnn rno rnr rnt roa rob roc roe ron roo ror rot rra rrb rrc rrn rrr rrt rta rtb rtc rte rtn rto rtr rtt taa tab tac tae tan tao tar tat tba tbb tbc tbe tbn tbo tbr tbt tca tcb tcc tce tcn tco tcr tct te- tea teb tec tee ten teo ter tet tna tnb tnc tne tnn tno tnr tnt to- toa tob toc toe ton too tor tot tra trb trc tre trn tro trr trt tta ttb ttc tte ttn tto ttr ttt