-er a-a a-b a-c a-t aaa aab aac aae aak aao aap aar aat ab- aba abb abc abe abk abo abp abr abt ac- aca acb acc ace ack aco acp acr act aea aeb aec aee aek aeo aep aer aet aka akb akc ake akk ako akp akr aoa aob aoc aoe aok aoo aop aor aot ap- apa apb apc ape apk apo app apr apt ar- ara arb arc are ark aro arp arr art at- ata atb atc ate ato atp atr att b-p baa bab bac bae bak bao bap bar bat bba bbb bbc bbe bbk bbo bbp bbr bbt bca bcb bcc bce bck bco bcp bcr bct be- bea beb bec bee bek beo bep ber bet bka bkb bkc bke bkk bko bkp bkr bkt boa bob boc boe bok boo bop bor bot bpa bpb bpc bpe bpo bpp bpr bpt bra brb bre brk bro brp brr brt bta btb btc bte btk bto btp btr btt c-- caa cab cac cae cak cao cap car cat cba cbb cbc cbe cbk cbo cbp cbr cbt cca ccb ccc cce cck cco ccp ccr cct ce- cea ceb cec cee cek ceo cep cer cet cka ckb ckc cko ckt co- coa cob coc coe cok coo cop cor cot cpa cpb cpc cpe cpk cpo cpp cpr cpt cra crb crc cre crk cro crp crr crt cta ctb ctc cte ctk cto ctp ctr ctt eaa eab eac eae eak eao eap ear eat eba ebb ebc ebe ebk ebo ebp ebr ebt ec- eca ecb ecc ece eck eco ecr ect eea eeb eec eee eek eeo eep eer eet eka ekb ekc eke eko ekp ekr ekt eo- eoa eob eoc eoe eok eoo eop eor eot ep- epa epb epc epe epo epp epr ept era erb erc ere erk ero erp err ert eta etb etc ete etk eto etp etr ett k-t ka- kaa kab kac kae kak kao kap kar kat kba kbb kbc kbe kbk kbo kbp kbr kca kcb kcc kce kck kcp kcr kct ke- kea keb kec kee kek keo kep ker ket kkb kkc kke kkk kkp kkr kkt koa kob koc koe kok koo kop kor kot kpa kpc kpe kpk kpo kpp kpr kpt kra krc krk kro krp krr krt kta ktb ktc kte ktk kto ktp ktr ktt oaa oab oac oae oak oao oap oar oat ob- oba obb obc obe obk obo obp obr obt oc- oca ocb occ ock oco ocp ocr oct oea oeb oec oee oeo oep oer oet oka okb okc oke okk oko okp okr oo- ooa oob ooc ook ooo oop oor oot op- opa opb opc ope opk opo opp opr opt or- ora orb orc ore ork oro orp orr ort ot- ota otb otc ote otk oto otp otr ott p-p paa pab pac pae pak pao pap par pat pba pbb pbc pbe pbk pbo pbp pbr pbt pca pcb pcc pce pck pco pcp pcr pct pea peb pec pee pek peo pep per pet pka pkb pkc pke pko pkp pkr pkt poa pob poc poe pok poo pop por pot ppa ppb ppc ppe ppk ppo ppp ppr ppt pra prb prc pre prk pro prp prr prt pt- pta ptb ptc pte ptk pto ptp ptr ptt ra- raa rab rac rae rak rao rap rar rat rba rbb rbc rbe rbk rbo rbp rbr rbt rca rcb rcc rce rco rcp rcr rct re- rea reb rec ree rek reo rep rer ret rkb rkc rke rkk rko rkp rkt roa rob roc roe rok roo rop ror rot rpa rpb rpc rpe rpk rpo rpp rpr rpt rra rrb rrc rrk rrp rrr rrt rta rtb rtc rte rtk rto rtp rtr rtt taa tab tac tae tak tao tap tar tat tba tbb tbc tbe tbk tbo tbp tbr tbt tca tcb tcc tce tck tco tcp tcr tct te- tea teb tec tee tek teo tep ter tet tka tkb tkc tke tkk tko tkp tkr tkt to- toa tob toc toe tok too top tor tot tpa tpb tpc tpe tpk tpo tpp tpr tpt tra trb trc tre trk tro trp trr trt tta ttb ttc tte ttk tto ttp ttr ttt