-er a-a a-b a-i aaa aab aae aai aan aao aar aax ab- aba abb abe abi abn abo abr abx aea aeb aee aei aen aeo aer aex ai- aia aib aie aii ain aio air aix an- ana anb ane ani ann ano anr anx aoa aob aoe aoi aon aoo aor aox ar- ara arb are ari arn aro arr arx ax- axa axe axi axn axo axr axx baa bab bae bai ban bao bar bax bba bbb bbe bbi bbn bbo bbr bbx be- bea beb bee bei ben beo ber bex bi- bia bib bie bii bin bio bir bix bna bnb bne bni bnn bno bnr bnx boa bob boe boi bon boo bor box bra brb bre bri brn bro brr brx bxb bxi bxn bxo bxx eaa eab eae eai ean eao ear eax eba ebb ebe ebi ebn ebo ebr ebx eea eeb eee een eeo eer eex eia eib eie eii ein eio eir eix en- ena enb ene eni enn eno enr eo- eoa eob eoe eoi eon eoo eor era erb ere eri ern ero err ex- exa exe exi exo exr exx ia- iaa iab iae iai ian iao iar iba ibb ibe ibi ibn ibo ibr ibx ie- iea iee iei ien ier iex iia iib iie iii iin iio iir iix in- ina inb ine ini inn ino inr inx io- ioa iob ioe ioi ion ioo ior ir- ira irb ire iri irn iro irr irx ixe ixi ixn n-i naa nab nae nai nan nao nar nax nba nbb nbe nbi nbn nbo nbr nbx ne- nea neb nee nei nen neo ner nex nia nib nie nii nin nio nir nix nna nnb nne nni nnn nno no- noa nob noe noi non noo nor nox nra nrb nre nri nrn nro nrr nrx o-i oaa oab oae oai oan oao oar oax ob- oba obb obe obi obn obo obr obx oea oeb oee oei oen oeo oer oex oia oib oie oii oin oio oir on- ona onb one oni onn ono onr onx oo- ooa oob ooi oon ooo oor oox or- ora orb ore ori orn oro orr orx ox- oxa oxb oxi oxn oxo oxx ra- raa rab rae rai ran rao rar rax rba rbb rbe rbi rbn rbo rbr rbx re- rea reb ree rei ren reo rer rex ria rib rie rii rin rio rir rix rna rnb rni rnn rno rnr roa rob roe roi ron roo ror rox rra rrb rri rrn rrr rxr xaa xan xar xbe xbr xbx xee xen xer xex xia xie xii xin xio xix xna xno xoa xoi xon xoo xor xox xrx xxi xxo xxx