-er a-a a-b aaa aab aae aak aan aao aar aau ab- aba abb abe abk abn abo abr abu aea aeb aee aek aen aeo aer aeu aka akb ake akk akn ako akr aku an- ana anb ane ank ann ano anr anu aoa aob aoe aok aon aoo aor aou ar- ara arb are ark arn aro arr aru au- aua aub aue auk aun auo aur b-u baa bab bae bak ban bao bar bau bba bbb bbe bbk bbn bbo bbr bbu be- bea beb bee bek ben beo ber beu bka bkb bke bkk bkn bko bkr bna bnb bne bnk bnn bno bnr bnu boa bob boe bok bon boo bor bou bra brb bre brk brn bro brr bru bua bub bue buk bun buo bur buu eaa eab eae eak ean eao ear eau eba ebb ebe ebk ebn ebo ebr ebu eea eeb eee eek een eeo eer eka ekb eke eko ekr eku en- ena enb ene enk enn eno enr enu eo- eoa eob eoe eok eon eoo eor eou era erb ere erk ern ero err eru eu- eua eub eue eun eur ka- kaa kab kae kak kan kao kar kau kba kbb kbe kbk kbn kbo kbr kbu ke- kea keb kee kek ken keo ker kkb kke kkk kkn kkr kku kn- kna kne knk knn kno knr knu koa kob koe kok kon koo kor kou kra krk krn kro krr kru kub kue kuk kun kur kuu naa nab nae nak nan nao nar nau nba nbb nbe nbk nbn nbo nbr nbu ne- nea neb nee nek nen neo ner neu nka nke nkk nkn nko nkr nku nna nnb nne nnk nnn nno nnu no- noa nob noe nok non noo nor nou nra nrb nre nrk nrn nro nrr nru nua nub nue nuk nun nuo nur nuu oaa oab oae oak oan oao oar oau ob- oba obb obe obk obn obo obr obu oea oeb oee oen oeo oer oka okb oke okk oko okr oku on- ona onb one onk onn ono onr onu oo- ooa oob ook oon ooo oor or- ora orb ore ork orn oro orr oru ou- oua oue ouk oun ouo our ra- raa rab rae rak ran rao rar rau rba rbb rbe rbk rbn rbo rbr rbu re- rea reb ree rek ren reo rer reu rkb rke rkk rko rku rna rnb rnn rno rnr rnu roa rob roe rok ron roo ror rou rra rrb rrk rrn rrr rru rua rub rue ruk run ruo rur ruu ua- uaa uab uae uak uan uao uar uau uba ubb ube ubk ubn ubo ubr ubu uea ueb uee uen uer uka ukb uke ukk ukn ukr uku un- una unb une unk unn uno unr unu uoa uob uoe uok uon uoo uor ur- ura urb ure urk urn uro urr uru uua uue uun uur uuu