-er a-a a-b a-c aaa aab aac aae aak aan aar aau ab- aba abb abc abe abk abn abr abu ac- aca acb acc ace ack acn acr acu aea aeb aec aee aek aen aer aeu aka akb akc ake akk akn akr aku an- ana anb anc ane ank ann anr anu ar- ara arb arc are ark arn arr aru au- aua aub auc aue auk aun aur b-u baa bab bac bae bak ban bar bau bba bbb bbc bbe bbk bbn bbr bbu bca bcb bcc bce bck bcn bcr bcu be- bea beb bec bee bek ben ber beu bka bkb bkc bke bkk bkn bkr bna bnb bnc bne bnk bnn bnr bnu bra brb bre brk brn brr bru bua bub buc bue buk bun bur buu c-- caa cab cac cae cak can car cau cba cbb cbc cbe cbk cbn cbr cbu cca ccb ccc cce cck ccn ccr ccu ce- cea ceb cec cee cek cen cer ceu cka ckb ckc cn- cna cnb cnc cne cnn cnr cnu cra crb crc cre crk crn crr cru cua cub cuc cue cuk cun cur cuu eaa eab eac eae eak ean ear eau eba ebb ebc ebe ebk ebn ebr ebu ec- eca ecb ecc ece eck ecn ecr ecu eea eeb eec eee eek een eer eka ekb ekc eke ekr eku en- ena enb enc ene enk enn enr enu era erb erc ere erk ern err eru eu- eua eub euc eue eun eur ka- kaa kab kac kae kak kan kar kau kba kbb kbc kbe kbk kbn kbr kbu kca kcb kcc kce kck kcn kcr kcu ke- kea keb kec kee kek ken ker kkb kkc kke kkk kkn kkr kku kn- kna knc kne knk knn knr knu kra krc krk krn krr kru kub kuc kue kuk kun kur kuu naa nab nac nae nak nan nar nau nba nbb nbc nbe nbk nbn nbr nbu nca ncb ncc nce nck ncn ncr ncu ne- nea neb nec nee nek nen ner neu nka nkc nke nkk nkn nkr nku nna nnb nnc nne nnk nnn nnu nra nrb nrc nre nrk nrn nrr nru nua nub nuc nue nuk nun nur nuu ra- raa rab rac rae rak ran rar rau rba rbb rbc rbe rbk rbn rbr rbu rca rcb rcc rce rcn rcr rcu re- rea reb rec ree rek ren rer reu rkb rkc rke rkk rku rna rnb rnc rnn rnr rnu rra rrb rrc rrk rrn rrr rru rua rub ruc rue ruk run rur ruu ua- uaa uab uac uae uak uan uar uau uba ubb ubc ube ubk ubn ubr ubu uca ucb ucc uce uck ucn ucr ucu uea ueb uec uee uen uer uka ukb ukc uke ukk ukn ukr uku un- una unb unc une unk unn unr unu ur- ura urb urc ure urk urn urr uru uua uuc uue uun uur uuu