-er a-a a-b a-t aaa aab aae aak aao aap aar aat ab- aba abb abe abk abo abp abr abt aea aeb aee aek aeo aep aer aet aka akb ake akk ako akp akr aoa aob aoe aok aoo aop aor aot ap- apa apb ape apk apo app apr apt ar- ara arb are ark aro arp arr art at- ata atb ate ato atp atr att b-p baa bab bae bak bao bap bar bat bba bbb bbe bbk bbo bbp bbr bbt be- bea beb bee bek beo bep ber bet bka bkb bke bkk bko bkp bkr bkt boa bob boe bok boo bop bor bot bpa bpb bpe bpo bpp bpr bpt bra brb bre brk bro brp brr brt bta btb bte btk bto btp btr btt eaa eab eae eak eao eap ear eat eba ebb ebe ebk ebo ebp ebr ebt eea eeb eee eek eeo eep eer eet eka ekb eke eko ekp ekr ekt eo- eoa eob eoe eok eoo eop eor eot ep- epa epb epe epo epp epr ept era erb ere erk ero erp err ert eta etb ete etk eto etp etr ett k-t ka- kaa kab kae kak kao kap kar kat kba kbb kbe kbk kbo kbp kbr ke- kea keb kee kek keo kep ker ket kkb kke kkk kkp kkr kkt koa kob koe kok koo kop kor kot kpa kpe kpk kpo kpp kpr kpt kra krk kro krp krr krt kta ktb kte ktk kto ktp ktr ktt oaa oab oae oak oao oap oar oat ob- oba obb obe obk obo obp obr obt oea oeb oee oeo oep oer oet oka okb oke okk oko okp okr oo- ooa oob ook ooo oop oor oot op- opa opb ope opk opo opp opr opt or- ora orb ore ork oro orp orr ort ot- ota otb ote otk oto otp otr ott p-p paa pab pae pak pao pap par pat pba pbb pbe pbk pbo pbp pbr pbt pea peb pee pek peo pep per pet pka pkb pke pko pkp pkr pkt poa pob poe pok poo pop por pot ppa ppb ppe ppk ppo ppp ppr ppt pra prb pre prk pro prp prr prt pt- pta ptb pte ptk pto ptp ptr ptt ra- raa rab rae rak rao rap rar rat rba rbb rbe rbk rbo rbp rbr rbt re- rea reb ree rek reo rep rer ret rkb rke rkk rko rkp rkt roa rob roe rok roo rop ror rot rpa rpb rpe rpk rpo rpp rpr rpt rra rrb rrk rrp rrr rrt rta rtb rte rtk rto rtp rtr rtt taa tab tae tak tao tap tar tat tba tbb tbe tbk tbo tbp tbr tbt te- tea teb tee tek teo tep ter tet tka tkb tke tkk tko tkp tkr tkt to- toa tob toe tok too top tor tot tpa tpb tpe tpk tpo tpp tpr tpt tra trb tre trk tro trp trr trt tta ttb tte ttk tto ttp ttr ttt