-er b-p bbb bbe bbk bbn bbo bbp bbr be- beb bee bek ben beo bep ber bkb bke bkk bkn bko bkp bkr bnb bne bnk bnn bno bnp bnr bob boe bok bon boo bop bor bpb bpe bpn bpo bpp bpr brb bre brk brn bro brp brr ebb ebe ebk ebn ebo ebp ebr eeb eee eek een eeo eep eer ekb eke eko ekp ekr en- enb ene enk enn eno enp enr eo- eob eoe eok eon eoo eop eor ep- epb epe epn epo epp epr erb ere erk ern ero erp err kbb kbe kbk kbn kbo kbp kbr ke- keb kee kek ken keo kep ker kkb kke kkk kkn kkp kkr kn- kne knk knn kno knp knr kob koe kok kon koo kop kor kpe kpk kpn kpo kpp kpr krk krn kro krp krr nbb nbe nbk nbn nbo nbp nbr ne- neb nee nek nen neo nep ner nke nkk nkn nko nkp nkr nnb nne nnk nnn nno nnp no- nob noe nok non noo nop nor npb npe npn npo npp npr nrb nre nrk nrn nro nrp nrr ob- obb obe obk obn obo obp obr oeb oee oen oeo oep oer okb oke okk oko okp okr on- onb one onk onn ono onp onr oo- oob ook oon ooo oop oor op- opb ope opk opn opo opp opr or- orb ore ork orn oro orp orr p-p pbb pbe pbk pbn pbo pbp pbr peb pee pek pen peo pep per pkb pke pkn pko pkp pkr pn- pnb pne pnk pnn pno pnp pnr pob poe pok pon poo pop por ppb ppe ppk ppn ppo ppp ppr prb pre prk prn pro prp prr rbb rbe rbk rbn rbo rbp rbr re- reb ree rek ren reo rep rer rkb rke rkk rko rkp rnb rnn rno rnp rnr rob roe rok ron roo rop ror rpb rpe rpk rpn rpo rpp rpr rrb rrk rrn rrp rrr