-er a-a a-b a-c aaa aab aac aae aak aar aau ab- aba abb abc abe abk abr abu ac- aca acb acc ace ack acr acu aea aeb aec aee aek aer aeu aka akb akc ake akk akr aku ar- ara arb arc are ark arr aru au- aua aub auc aue auk aur b-u baa bab bac bae bak bar bau bba bbb bbc bbe bbk bbr bbu bca bcb bcc bce bck bcr bcu be- bea beb bec bee bek ber beu bka bkb bkc bke bkk bkr bra brb bre brk brr bru bua bub buc bue buk bur buu c-- caa cab cac cae cak car cau cba cbb cbc cbe cbk cbr cbu cca ccb ccc cce cck ccr ccu ce- cea ceb cec cee cek cer ceu cka ckb ckc cra crb crc cre crk crr cru cua cub cuc cue cuk cur cuu eaa eab eac eae eak ear eau eba ebb ebc ebe ebk ebr ebu ec- eca ecb ecc ece eck ecr ecu eea eeb eec eee eek eer eka ekb ekc eke ekr eku era erb erc ere erk err eru eu- eua eub euc eue eur ka- kaa kab kac kae kak kar kau kba kbb kbc kbe kbk kbr kbu kca kcb kcc kce kck kcr kcu ke- kea keb kec kee kek ker kkb kkc kke kkk kkr kku kra krc krk krr kru kub kuc kue kuk kur kuu ra- raa rab rac rae rak rar rau rba rbb rbc rbe rbk rbr rbu rca rcb rcc rce rcr rcu re- rea reb rec ree rek rer reu rkb rkc rke rkk rku rra rrb rrc rrk rrr rru rua rub ruc rue ruk rur ruu ua- uaa uab uac uae uak uar uau uba ubb ubc ube ubk ubr ubu uca ucb ucc uce uck ucr ucu uea ueb uec uee uer uka ukb ukc uke ukk ukr uku ur- ura urb urc ure urk urr uru uua uuc uue uur uuu