a-a a-b a-i aaa aab aaf aai aan aao aar ab- aba abb abf abi abn abo abr af- afa afb aff afi afn afo afr ai- aia aib aif aii ain aio air an- ana anb anf ani ann ano anr aoa aob aof aoi aon aoo aor ar- ara arb arf ari arn aro arr baa bab baf bai ban bao bar bba bbb bbf bbi bbn bbo bbr bfa bfb bff bfi bfn bfo bfr bi- bia bib bif bii bin bio bir bna bnb bnf bni bnn bno bnr boa bob bof boi bon boo bor bra brb brf bri brn bro brr faa fab faf fai fan fao far fba fbb fbf fbi fbn fbo fbr ffa fff ffi ffn ffo ffr fia fib fif fii fin fir fna fnb fnf fni fnn fnr foa fob fof foi fon foo for fra frb frf fri frn fro frr i-f ia- iaa iab iaf iai ian iao iar iba ibb ibf ibi ibn ibo ibr ifa ifb iff ifi ifn ifo ifr iia iib iif iii iin iio iir in- ina inb inf ini inn ino inr io- ioa iob iof ioi ion ioo ior ir- ira irb irf iri irn iro irr n-i naa nab naf nai nan nao nar nba nbb nbf nbi nbn nbo nbr nfa nfb nff nfi nfn nfo nfr nia nib nif nii nin nio nir nna nnb nnf nni nnn nno no- noa nob nof noi non noo nor nra nrb nrf nri nrn nro nrr o-i oaa oab oaf oai oan oao oar ob- oba obb obf obi obn obo obr of- ofa ofb off ofi ofn ofo ofr oia oib oif oii oin oio oir on- ona onb onf oni onn ono onr oo- ooa oob oof ooi oon ooo oor or- ora orb orf ori orn oro orr ra- raa rab raf rai ran rao rar rba rbb rbf rbi rbn rbo rbr rfa rfb rff rfi rfn rfo rfr ria rib rif rii rin rio rir rna rnb rni rnn rno rnr roa rob rof roi ron roo ror rra rrb rrf rri rrn rrr