-er a-a a-b a-c aaa aab aac aae aan aao aar aau ab- aba abb abc abe abn abo abr abu ac- aca acb acc ace acn aco acr acu aea aeb aec aee aen aeo aer aeu an- ana anb anc ane ann ano anr anu aoa aob aoc aoe aon aoo aor aou ar- ara arb arc are arn aro arr aru au- aua aub auc aue aun auo aur b-u baa bab bac bae ban bao bar bau bba bbb bbc bbe bbn bbo bbr bbu bca bcb bcc bce bcn bco bcr bcu be- bea beb bec bee ben beo ber beu bna bnb bnc bne bnn bno bnr bnu boa bob boc boe bon boo bor bou bra brb bre brn bro brr bru bua bub buc bue bun buo bur buu c-- caa cab cac cae can cao car cau cba cbb cbc cbe cbn cbo cbr cbu cca ccb ccc cce ccn cco ccr ccu ce- cea ceb cec cee cen ceo cer ceu cn- cna cnb cnc cne cnn cno cnr cnu co- coa cob coc coe con coo cor cou cra crb crc cre crn cro crr cru cua cub cuc cue cun cuo cur cuu eaa eab eac eae ean eao ear eau eba ebb ebc ebe ebn ebo ebr ebu ec- eca ecb ecc ece ecn eco ecr ecu eea eeb eec eee een eeo eer en- ena enb enc ene enn eno enr enu eo- eoa eob eoc eoe eon eoo eor eou era erb erc ere ern ero err eru eu- eua eub euc eue eun eur naa nab nac nae nan nao nar nau nba nbb nbc nbe nbn nbo nbr nbu nca ncb ncc nce ncn nco ncr ncu ne- nea neb nec nee nen neo ner neu nna nnb nnc nne nnn nno nnu no- noa nob noc noe non noo nor nou nra nrb nrc nre nrn nro nrr nru nua nub nuc nue nun nuo nur nuu oaa oab oac oae oan oao oar oau ob- oba obb obc obe obn obo obr obu oc- oca ocb occ ocn oco ocr ocu oea oeb oec oee oen oeo oer on- ona onb onc one onn ono onr onu oo- ooa oob ooc oon ooo oor or- ora orb orc ore orn oro orr oru ou- oua ouc oue oun ouo our ra- raa rab rac rae ran rao rar rau rba rbb rbc rbe rbn rbo rbr rbu rca rcb rcc rce rcn rco rcr rcu re- rea reb rec ree ren reo rer reu rna rnb rnc rnn rno rnr rnu roa rob roc roe ron roo ror rou rra rrb rrc rrn rrr rru rua rub ruc rue run ruo rur ruu ua- uaa uab uac uae uan uao uar uau uba ubb ubc ube ubn ubo ubr ubu uca ucb ucc uce ucn uco ucr ucu uea ueb uec uee uen uer un- una unb unc une unn uno unr unu uoa uob uoc uoe uon uoo uor ur- ura urb urc ure urn uro urr uru uua uuc uue uun uur uuu