-er a-a a-b a-c a-t aaa aab aac aae aap aar aat ab- aba abb abc abe abp abr abt ac- aca acb acc ace acp acr act aea aeb aec aee aep aer aet ap- apa apb apc ape app apr apt ar- ara arb arc are arp arr art at- ata atb atc ate atp atr att b-p baa bab bac bae bap bar bat bba bbb bbc bbe bbp bbr bbt bca bcb bcc bce bcp bcr bct be- bea beb bec bee bep ber bet bpa bpb bpc bpe bpp bpr bpt bra brb bre brp brr brt bta btb btc bte btp btr btt c-- caa cab cac cae cap car cat cba cbb cbc cbe cbp cbr cbt cca ccb ccc cce ccp ccr cct ce- cea ceb cec cee cep cer cet cpa cpb cpc cpe cpp cpr cpt cra crb crc cre crp crr crt cta ctb ctc cte ctp ctr ctt eaa eab eac eae eap ear eat eba ebb ebc ebe ebp ebr ebt ec- eca ecb ecc ece ecr ect eea eeb eec eee eep eer eet ep- epa epb epc epe epp epr ept era erb erc ere erp err ert eta etb etc ete etp etr ett p-p paa pab pac pae pap par pat pba pbb pbc pbe pbp pbr pbt pca pcb pcc pce pcp pcr pct pea peb pec pee pep per pet ppa ppb ppc ppe ppp ppr ppt pra prb prc pre prp prr prt pt- pta ptb ptc pte ptp ptr ptt ra- raa rab rac rae rap rar rat rba rbb rbc rbe rbp rbr rbt rca rcb rcc rce rcp rcr rct re- rea reb rec ree rep rer ret rpa rpb rpc rpe rpp rpr rpt rra rrb rrc rrp rrr rrt rta rtb rtc rte rtp rtr rtt taa tab tac tae tap tar tat tba tbb tbc tbe tbp tbr tbt tca tcb tcc tce tcp tcr tct te- tea teb tec tee tep ter tet tpa tpb tpc tpe tpp tpr tpt tra trb trc tre trp trr trt tta ttb ttc tte ttp ttr ttt