-er a-a a-b a-c a-t aaa aab aac aae aan aap aar aat ab- aba abb abc abe abn abp abr abt ac- aca acb acc ace acn acp acr act aea aeb aec aee aen aep aer aet an- ana anb anc ane ann anp anr ant ap- apa apb apc ape apn app apr apt ar- ara arb arc are arn arp arr art at- ata atb atc ate atn atp atr att b-p baa bab bac bae ban bap bar bat bba bbb bbc bbe bbn bbp bbr bbt bca bcb bcc bce bcn bcp bcr bct be- bea beb bec bee ben bep ber bet bna bnb bnc bne bnn bnp bnr bnt bpa bpb bpc bpe bpn bpp bpr bpt bra brb bre brn brp brr brt bta btb btc bte btn btp btr btt c-- caa cab cac cae can cap car cat cba cbb cbc cbe cbn cbp cbr cbt cca ccb ccc cce ccn ccp ccr cct ce- cea ceb cec cee cen cep cer cet cn- cna cnb cnc cne cnn cnp cnr cnt cpa cpb cpc cpe cpn cpp cpr cpt cra crb crc cre crn crp crr crt cta ctb ctc cte ctn ctp ctr ctt eaa eab eac eae ean eap ear eat eba ebb ebc ebe ebn ebp ebr ebt ec- eca ecb ecc ece ecn ecr ect eea eeb eec eee een eep eer eet en- ena enb enc ene enn enp enr ent ep- epa epb epc epe epn epp epr ept era erb erc ere ern erp err ert eta etb etc ete etn etp etr ett naa nab nac nae nan nap nar nat nba nbb nbc nbe nbn nbp nbr nbt nca ncb ncc nce ncn ncp ncr nct ne- nea neb nec nee nen nep ner net nna nnb nnc nne nnn nnp nnt npa npb npc npe npn npp npr npt nra nrb nrc nre nrn nrp nrr nrt nta ntb ntc nte ntn ntp ntr ntt p-p paa pab pac pae pan pap par pat pba pbb pbc pbe pbn pbp pbr pbt pca pcb pcc pce pcn pcp pcr pct pea peb pec pee pen pep per pet pn- pna pnb pnc pne pnn pnp pnr pnt ppa ppb ppc ppe ppn ppp ppr ppt pra prb prc pre prn prp prr prt pt- pta ptb ptc pte ptn ptp ptr ptt ra- raa rab rac rae ran rap rar rat rba rbb rbc rbe rbn rbp rbr rbt rca rcb rcc rce rcn rcp rcr rct re- rea reb rec ree ren rep rer ret rna rnb rnc rnn rnp rnr rnt rpa rpb rpc rpe rpn rpp rpr rpt rra rrb rrc rrn rrp rrr rrt rta rtb rtc rte rtn rtp rtr rtt taa tab tac tae tan tap tar tat tba tbb tbc tbe tbn tbp tbr tbt tca tcb tcc tce tcn tcp tcr tct te- tea teb tec tee ten tep ter tet tna tnb tnc tne tnn tnp tnr tnt tpa tpb tpc tpe tpn tpp tpr tpt tra trb trc tre trn trp trr trt tta ttb ttc tte ttn ttp ttr ttt