-er b-p bbb bbe bbk bbo bbp bbr bbt be- beb bee bek beo bep ber bet bkb bke bkk bko bkp bkr bkt bob boe bok boo bop bor bot bpb bpe bpo bpp bpr bpt brb bre brk bro brp brr brt btb bte btk bto btp btr btt ebb ebe ebk ebo ebp ebr ebt eeb eee eek eeo eep eer eet ekb eke eko ekp ekr ekt eo- eob eoe eok eoo eop eor eot ep- epb epe epo epp epr ept erb ere erk ero erp err ert etb ete etk eto etp etr ett k-t kbb kbe kbk kbo kbp kbr ke- keb kee kek keo kep ker ket kkb kke kkk kkp kkr kkt kob koe kok koo kop kor kot kpe kpk kpo kpp kpr kpt krk kro krp krr krt ktb kte ktk kto ktp ktr ktt ob- obb obe obk obo obp obr obt oeb oee oeo oep oer oet okb oke okk oko okp okr oo- oob ook ooo oop oor oot op- opb ope opk opo opp opr opt or- orb ore ork oro orp orr ort ot- otb ote otk oto otp otr ott p-p pbb pbe pbk pbo pbp pbr pbt peb pee pek peo pep per pet pkb pke pko pkp pkr pkt pob poe pok poo pop por pot ppb ppe ppk ppo ppp ppr ppt prb pre prk pro prp prr prt pt- ptb pte ptk pto ptp ptr ptt rbb rbe rbk rbo rbp rbr rbt re- reb ree rek reo rep rer ret rkb rke rkk rko rkp rkt rob roe rok roo rop ror rot rpb rpe rpk rpo rpp rpr rpt rrb rrk rrp rrr rrt rtb rte rtk rto rtp rtr rtt tbb tbe tbk tbo tbp tbr tbt te- teb tee tek teo tep ter tet tkb tke tkk tko tkp tkr tkt to- tob toe tok too top tor tot tpb tpe tpk tpo tpp tpr tpt trb tre trk tro trp trr trt ttb tte ttk tto ttp ttr ttt