a-a a-b aaa aab aad aan aao aar aax ab- aba abb abd abn abo abr abx ad- ada adb add adn ado adr adx an- ana anb and ann ano anr anx aoa aob aod aon aoo aor aox ar- ara arb ard arn aro arr arx ax- axa axn axo axr axx baa bab bad ban bao bar bax bba bbb bbd bbn bbo bbr bbx bda bdb bdd bdo bdr bdx bna bnb bnd bnn bno bnr bnx boa bob bod bon boo bor box bra brb brd brn bro brr brx bxb bxd bxn bxo bxx daa dab dad dan dao dar dax dba dbb dbd dbn dbo dbr dbx dda ddb ddd ddn ddo ddr ddx dna dnb dnd dnn dno dnr doa dob dod don doo dor dox dra drb drd drn dro drr drx dxd dxn dxo dxr dxx naa nab nad nan nao nar nax nba nbb nbd nbn nbo nbr nbx nda ndb ndd ndn ndo ndr nna nnb nnn nno no- noa nob nod non noo nor nox nra nrb nrd nrn nro nrr nrx nxd oaa oab oad oan oao oar oax ob- oba obb obd obn obo obr obx oda odb odd odn odo odr on- ona onb ond onn ono onr onx oo- ooa oob ood oon ooo oor oox or- ora orb ord orn oro orr orx ox- oxa oxb oxn oxo oxx ra- raa rab rad ran rao rar rax rba rbb rbd rbn rbo rbr rbx rda rdb rdd rdn rdo rdr rdx rna rnb rnd rnn rno rnr roa rob rod ron roo ror rox rra rrb rrd rrn rrr rxr xaa xad xan xar xbr xbx xda xdb xdr xna xno xoa xod xon xoo xor xox xrd xrx xxo xxx