-er b-u bbb bbc bbe bbr bbu bcb bcc bce bcr bcu bcz be- beb bec bee ber beu bez brb bre brr bru brz bub buc bue bur buu buz bze bzr bzu bzz c-- cbb cbc cbe cbr cbu cbz ccb ccc cce ccr ccu ccz ce- ceb cec cee cer ceu cez crb crc cre crr cru crz cub cuc cue cur cuu cuz cz- czc cze ebb ebc ebe ebr ebu ec- ecb ecc ece ecr ecu eeb eec eee eer erb erc ere err eru erz eu- eub euc eue eur eze ezr ezz rbb rbc rbe rbr rbu rcb rcc rce rcr rcu re- reb rec ree rer reu rez rrb rrc rrr rru rub ruc rue rur ruu ruz rzb rze ubb ubc ube ubr ubu ucb ucc uce ucr ucu ueb uec uee uer ur- urb urc ure urr uru urz uuc uue uur uuu uzb uzu zbb zbc zbr zce zeb zec zee zer zez zub zuc zur zuz zzr zzz