-er a-a a-b aaa aab aae aan aar aau aax ab- aba abb abe abn abr abu abx aea aeb aee aen aer aeu aex an- ana anb ane ann anr anu anx ar- ara arb are arn arr aru arx au- aua aub aue aun aur aux ax- axa axe axn axr axx b-u baa bab bae ban bar bau bax bba bbb bbe bbn bbr bbu bbx be- bea beb bee ben ber beu bex bna bnb bne bnn bnr bnu bnx bra brb bre brn brr bru brx bua bub bue bun bur buu bux bxb bxn bxx eaa eab eae ean ear eau eax eba ebb ebe ebn ebr ebu ebx eea eeb eee een eer eex en- ena enb ene enn enr enu era erb ere ern err eru eu- eua eub eue eun eur eux ex- exa exe exr exu exx naa nab nae nan nar nau nax nba nbb nbe nbn nbr nbu nbx ne- nea neb nee nen ner neu nex nna nnb nne nnn nnu nra nrb nre nrn nrr nru nrx nua nub nue nun nur nuu nux ra- raa rab rae ran rar rau rax rba rbb rbe rbn rbr rbu rbx re- rea reb ree ren rer reu rex rna rnb rnn rnr rnu rra rrb rrn rrr rru rua rub rue run rur ruu rux rxr ua- uaa uab uae uan uar uau uba ubb ube ubn ubr ubu ubx uea ueb uee uen uer un- una unb une unn unr unu unx ur- ura urb ure urn urr uru urx uua uue uun uur uuu uxb uxr uxu xaa xan xar xau xbe xbr xbx xee xen xer xeu xex xna xnu xrx xue xun xxx