-er b-u bbb bbc bbd bbe bbk bbr bbu bcb bcc bcd bce bck bcr bcu bdb bdc bdd bde bdk bdr bdu be- beb bec bed bee bek ber beu bkb bkc bke bkk bkr brb brd bre brk brr bru bub buc bud bue buk bur buu c-- cbb cbc cbd cbe cbk cbr cbu ccb ccc ccd cce cck ccr ccu cdb cdc cdd cde cdk cdr cdu ce- ceb cec ced cee cek cer ceu ckb ckc ckd crb crc crd cre crk crr cru cub cuc cud cue cuk cur cuu dbb dbc dbd dbe dbk dbr dbu dcb dcc dcd dce dck dcr dcu ddb ddc ddd dde ddk ddr ddu de- deb dec ded dee dek der deu dkb dkc dke dkk dkr dku drb drc drd dre drk drr dru dub duc dud due duk dur ebb ebc ebd ebe ebk ebr ebu ec- ecb ecc ecd ece eck ecr ecu ed- edb edc edd ede edk edr edu eeb eec eed eee eek eer ekb ekc ekd eke ekr eku erb erc erd ere erk err eru eu- eub euc eud eue eur kbb kbc kbd kbe kbk kbr kbu kcb kcc kcd kce kck kcr kcu kdb kdc kde kdk kdr kdu ke- keb kec ked kee kek ker kkb kkc kke kkk kkr kku krc krd krk krr kru kub kuc kud kue kuk kur kuu rbb rbc rbd rbe rbk rbr rbu rcb rcc rcd rce rcr rcu rdb rdc rdd rde rdr rdu re- reb rec red ree rek rer reu rkb rkc rke rkk rku rrb rrc rrd rrk rrr rru rub ruc rud rue ruk rur ruu ubb ubc ube ubk ubr ubu ucb ucc ucd uce uck ucr ucu udb udc udd ude udk udr udu ueb uec ued uee uer ukb ukc uke ukk ukr uku ur- urb urc urd ure urk urr uru uuc uue uur uuu