a-a a-b aaa aab aad aaf aan aao aar ab- aba abb abd abf abn abo abr ad- ada adb add adf adn ado adr af- afa afb afd aff afn afo afr an- ana anb and anf ann ano anr aoa aob aod aof aon aoo aor ar- ara arb ard arf arn aro arr baa bab bad baf ban bao bar bba bbb bbd bbf bbn bbo bbr bda bdb bdd bdf bdo bdr bfa bfb bfd bff bfn bfo bfr bna bnb bnd bnf bnn bno bnr boa bob bod bof bon boo bor bra brb brd brf brn bro brr daa dab dad daf dan dao dar dba dbb dbd dbf dbn dbo dbr dda ddb ddd ddf ddn ddo ddr dfa dfb dfd dff dfn dfo dfr dna dnb dnd dnf dnn dno dnr doa dob dod dof don doo dor dra drb drd drn dro drr faa fab fad faf fan fao far fba fbb fbd fbf fbn fbo fbr fda fdb fdd fdf fdn fdo fdr ffa ffd fff ffn ffo ffr fna fnb fnd fnf fnn fnr foa fob fof fon foo for fra frb frd frf frn fro frr naa nab nad naf nan nao nar nba nbb nbd nbf nbn nbo nbr nda ndb ndd ndf ndn ndo ndr nfa nfb nfd nff nfn nfo nfr nna nnb nnf nnn nno no- noa nob nod nof non noo nor nra nrb nrd nrf nrn nro nrr oaa oab oad oaf oan oao oar ob- oba obb obd obf obn obo obr oda odb odd odf odn odo odr of- ofa ofb ofd off ofn ofo ofr on- ona onb ond onf onn ono onr oo- ooa oob ood oof oon ooo oor or- ora orb ord orf orn oro orr ra- raa rab rad raf ran rao rar rba rbb rbd rbf rbn rbo rbr rda rdb rdd rdf rdn rdo rdr rfa rfb rfd rff rfn rfo rfr rna rnb rnd rnn rno rnr roa rob rod rof ron roo ror rra rrb rrd rrf rrn rrr