-er a-a a-b aaa aab aae aan aao aar aau aax ab- aba abb abe abn abo abr abu abx aea aeb aee aen aeo aer aeu aex an- ana anb ane ann ano anr anu anx aoa aob aoe aon aoo aor aou aox ar- ara arb are arn aro arr aru arx au- aua aub aue aun auo aur aux ax- axa axe axn axo axr axx b-u baa bab bae ban bao bar bau bax bba bbb bbe bbn bbo bbr bbu bbx be- bea beb bee ben beo ber beu bex bna bnb bne bnn bno bnr bnu bnx boa bob boe bon boo bor bou box bra brb bre brn bro brr bru brx bua bub bue bun buo bur buu bux bxb bxn bxo bxx eaa eab eae ean eao ear eau eax eba ebb ebe ebn ebo ebr ebu ebx eea eeb eee een eeo eer eex en- ena enb ene enn eno enr enu eo- eoa eob eoe eon eoo eor eou era erb ere ern ero err eru eu- eua eub eue eun eur eux ex- exa exe exo exr exu exx naa nab nae nan nao nar nau nax nba nbb nbe nbn nbo nbr nbu nbx ne- nea neb nee nen neo ner neu nex nna nnb nne nnn nno nnu no- noa nob noe non noo nor nou nox nra nrb nre nrn nro nrr nru nrx nua nub nue nun nuo nur nuu nux oaa oab oae oan oao oar oau oax ob- oba obb obe obn obo obr obu obx oea oeb oee oen oeo oer oex on- ona onb one onn ono onr onu onx oo- ooa oob oon ooo oor oox or- ora orb ore orn oro orr oru orx ou- oua oue oun ouo our ox- oxa oxb oxn oxo oxx ra- raa rab rae ran rao rar rau rax rba rbb rbe rbn rbo rbr rbu rbx re- rea reb ree ren reo rer reu rex rna rnb rnn rno rnr rnu roa rob roe ron roo ror rou rox rra rrb rrn rrr rru rua rub rue run ruo rur ruu rux rxr ua- uaa uab uae uan uao uar uau uba ubb ube ubn ubo ubr ubu ubx uea ueb uee uen uer un- una unb une unn uno unr unu unx uoa uob uoe uon uoo uor uox ur- ura urb ure urn uro urr uru urx uua uue uun uur uuu uxb uxo uxr uxu xaa xan xar xau xbe xbr xbx xee xen xer xeu xex xna xno xnu xoa xon xoo xor xox xrx xue xun xxo xxx