-er a-a a-b aaa aab aae aaf aan aao aar ab- aba abb abe abf abn abo abr aea aeb aee aef aen aeo aer af- afa afb afe aff afn afo afr an- ana anb ane anf ann ano anr aoa aob aoe aof aon aoo aor ar- ara arb are arf arn aro arr baa bab bae baf ban bao bar bba bbb bbe bbf bbn bbo bbr be- bea beb bee bef ben beo ber bfa bfb bfe bff bfn bfo bfr bna bnb bne bnf bnn bno bnr boa bob boe bof bon boo bor bra brb bre brf brn bro brr eaa eab eae eaf ean eao ear eba ebb ebe ebf ebn ebo ebr eea eeb eee eef een eeo eer ef- efa efb efe eff efo efr en- ena enb ene enf enn eno enr eo- eoa eob eoe eof eon eoo eor era erb ere erf ern ero err faa fab fae faf fan fao far fba fbb fbe fbf fbn fbo fbr fea feb fee fef fen feo fer ffa ffe fff ffn ffo ffr fna fnb fne fnf fnn fnr foa fob foe fof fon foo for fra frb fre frf frn fro frr naa nab nae naf nan nao nar nba nbb nbe nbf nbn nbo nbr ne- nea neb nee nef nen neo ner nfa nfb nfe nff nfn nfo nfr nna nnb nne nnf nnn nno no- noa nob noe nof non noo nor nra nrb nre nrf nrn nro nrr oaa oab oae oaf oan oao oar ob- oba obb obe obf obn obo obr oea oeb oee oef oen oeo oer of- ofa ofb ofe off ofn ofo ofr on- ona onb one onf onn ono onr oo- ooa oob oof oon ooo oor or- ora orb ore orf orn oro orr ra- raa rab rae raf ran rao rar rba rbb rbe rbf rbn rbo rbr re- rea reb ree ref ren reo rer rfa rfb rfe rff rfn rfo rfr rna rnb rnn rno rnr roa rob roe rof ron roo ror rra rrb rrf rrn rrr