a-a a-b a-i aaa aab aad aaf aai aao aar ab- aba abb abd abf abi abo abr ad- ada adb add adf adi ado adr af- afa afb afd aff afi afo afr ai- aia aib aid aif aii aio air aoa aob aod aof aoi aoo aor ar- ara arb ard arf ari aro arr baa bab bad baf bai bao bar bba bbb bbd bbf bbi bbo bbr bda bdb bdd bdf bdi bdo bdr bfa bfb bfd bff bfi bfo bfr bi- bia bib bid bif bii bio bir boa bob bod bof boi boo bor bra brb brd brf bri bro brr daa dab dad daf dai dao dar dba dbb dbd dbf dbi dbo dbr dda ddb ddd ddf ddi ddo ddr dfa dfb dfd dff dfi dfo dfr di- dia dib did dif dii dio dir doa dob dod dof doi doo dor dra drb drd dri dro drr faa fab fad faf fai fao far fba fbb fbd fbf fbi fbo fbr fda fdb fdd fdf fdi fdo fdr ffa ffd fff ffi ffo ffr fia fib fid fif fii fir foa fob fof foi foo for fra frb frd frf fri fro frr i-d i-f ia- iaa iab iad iaf iai iao iar iba ibb ibd ibf ibi ibo ibr ida idb idd idf idi ido idr ifa ifb ifd iff ifi ifo ifr iia iib iid iif iii iio iir io- ioa iob iod iof ioi ioo ior ir- ira irb ird irf iri iro irr o-i oaa oab oad oaf oai oao oar ob- oba obb obd obf obi obo obr oda odb odd odf odi odo odr of- ofa ofb ofd off ofi ofo ofr oia oib oid oif oii oio oir oo- ooa oob ood oof ooi ooo oor or- ora orb ord orf ori oro orr ra- raa rab rad raf rai rao rar rba rbb rbd rbf rbi rbo rbr rda rdb rdd rdf rdi rdo rdr rfa rfb rfd rff rfi rfo rfr ria rib rid rif rii rio rir roa rob rod rof roi roo ror rra rrb rrd rrf rri rrr