-er a-a a-b a-t aaa aab aae aao aap aar aat aax ab- aba abb abe abo abp abr abt abx aea aeb aee aeo aep aer aet aex aoa aob aoe aoo aop aor aot aox ap- apa apb ape apo app apr apt apx ar- ara arb are aro arp arr art arx at- ata atb ate ato atp atr att atx ax- axa axe axo axp axr axt axx b-p baa bab bae bao bap bar bat bax bba bbb bbe bbo bbp bbr bbt bbx be- bea beb bee beo bep ber bet bex boa bob boe boo bop bor bot box bpa bpb bpe bpo bpp bpr bpt bpx bra brb bre bro brp brr brt brx bta btb bte bto btp btr btt btx bxb bxo bxx eaa eab eae eao eap ear eat eax eba ebb ebe ebo ebp ebr ebt ebx eea eeb eee eeo eep eer eet eex eo- eoa eob eoe eoo eop eor eot ep- epa epb epe epo epp epr ept epx era erb ere ero erp err ert eta etb ete eto etp etr ett etx ex- exa exe exo exp exr ext exx oaa oab oae oao oap oar oat oax ob- oba obb obe obo obp obr obt obx oea oeb oee oeo oep oer oet oex oo- ooa oob ooo oop oor oot oox op- opa opb ope opo opp opr opt opx or- ora orb ore oro orp orr ort orx ot- ota otb ote oto otp otr ott ox- oxa oxb oxo oxt oxx p-p paa pab pae pao pap par pat pax pba pbb pbe pbo pbp pbr pbt pbx pea peb pee peo pep per pet pex poa pob poe poo pop por pot pox ppa ppb ppe ppo ppp ppr ppt ppx pra prb pre pro prp prr prt prx pt- pta ptb pte pto ptp ptr ptt ptx pxe pxr pxt ra- raa rab rae rao rap rar rat rax rba rbb rbe rbo rbp rbr rbt rbx re- rea reb ree reo rep rer ret rex roa rob roe roo rop ror rot rox rpa rpb rpe rpo rpp rpr rpt rpx rra rrb rrp rrr rrt rta rtb rte rto rtp rtr rtt rtx rxp rxr t-x taa tab tae tao tap tar tat tax tba tbb tbe tbo tbp tbr tbt te- tea teb tee teo tep ter tet tex to- toa tob toe too top tor tot tox tpa tpb tpe tpo tpp tpr tpt tpx tra trb tre tro trp trr trt trx tta ttb tte tto ttp ttr ttt ttx txe txt xaa xap xar xat xbe xbr xbx xee xep xer xet xex xoa xoo xop xor xot xox xpa xpb xpe xpo xpp xpt xrt xrx xtp xtr xtx xxo xxp xxx