-er a-a a-b aaa aab aae aan aao aap aar ab- aba abb abe abn abo abp abr aea aeb aee aen aeo aep aer an- ana anb ane ann ano anp anr aoa aob aoe aon aoo aop aor ap- apa apb ape apn apo app apr ar- ara arb are arn aro arp arr b-p baa bab bae ban bao bap bar bba bbb bbe bbn bbo bbp bbr be- bea beb bee ben beo bep ber bna bnb bne bnn bno bnp bnr boa bob boe bon boo bop bor bpa bpb bpe bpn bpo bpp bpr bra brb bre brn bro brp brr eaa eab eae ean eao eap ear eba ebb ebe ebn ebo ebp ebr eea eeb eee een eeo eep eer en- ena enb ene enn eno enp enr eo- eoa eob eoe eon eoo eop eor ep- epa epb epe epn epo epp epr era erb ere ern ero erp err naa nab nae nan nao nap nar nba nbb nbe nbn nbo nbp nbr ne- nea neb nee nen neo nep ner nna nnb nne nnn nno nnp no- noa nob noe non noo nop nor npa npb npe npn npo npp npr nra nrb nre nrn nro nrp nrr oaa oab oae oan oao oap oar ob- oba obb obe obn obo obp obr oea oeb oee oen oeo oep oer on- ona onb one onn ono onp onr oo- ooa oob oon ooo oop oor op- opa opb ope opn opo opp opr or- ora orb ore orn oro orp orr p-p paa pab pae pan pao pap par pba pbb pbe pbn pbo pbp pbr pea peb pee pen peo pep per pn- pna pnb pne pnn pno pnp pnr poa pob poe pon poo pop por ppa ppb ppe ppn ppo ppp ppr pra prb pre prn pro prp prr ra- raa rab rae ran rao rap rar rba rbb rbe rbn rbo rbp rbr re- rea reb ree ren reo rep rer rna rnb rnn rno rnp rnr roa rob roe ron roo rop ror rpa rpb rpe rpn rpo rpp rpr rra rrb rrn rrp rrr