-er a-a a-b a-t aaa aab aae aao aap aar aat ab- aba abb abe abo abp abr abt aea aeb aee aeo aep aer aet aoa aob aoe aoo aop aor aot ap- apa apb ape apo app apr apt ar- ara arb are aro arp arr art at- ata atb ate ato atp atr att b-p baa bab bae bao bap bar bat bba bbb bbe bbo bbp bbr bbt be- bea beb bee beo bep ber bet boa bob boe boo bop bor bot bpa bpb bpe bpo bpp bpr bpt bra brb bre bro brp brr brt bta btb bte bto btp btr btt eaa eab eae eao eap ear eat eba ebb ebe ebo ebp ebr ebt eea eeb eee eeo eep eer eet eo- eoa eob eoe eoo eop eor eot ep- epa epb epe epo epp epr ept era erb ere ero erp err ert eta etb ete eto etp etr ett oaa oab oae oao oap oar oat ob- oba obb obe obo obp obr obt oea oeb oee oeo oep oer oet oo- ooa oob ooo oop oor oot op- opa opb ope opo opp opr opt or- ora orb ore oro orp orr ort ot- ota otb ote oto otp otr ott p-p paa pab pae pao pap par pat pba pbb pbe pbo pbp pbr pbt pea peb pee peo pep per pet poa pob poe poo pop por pot ppa ppb ppe ppo ppp ppr ppt pra prb pre pro prp prr prt pt- pta ptb pte pto ptp ptr ptt ra- raa rab rae rao rap rar rat rba rbb rbe rbo rbp rbr rbt re- rea reb ree reo rep rer ret roa rob roe roo rop ror rot rpa rpb rpe rpo rpp rpr rpt rra rrb rrp rrr rrt rta rtb rte rto rtp rtr rtt taa tab tae tao tap tar tat tba tbb tbe tbo tbp tbr tbt te- tea teb tee teo tep ter tet to- toa tob toe too top tor tot tpa tpb tpe tpo tpp tpr tpt tra trb tre tro trp trr trt tta ttb tte tto ttp ttr ttt