-er bbb bbc bbe bbk bbn bbr bcb bcc bce bck bcn bcr be- beb bec bee bek ben ber bkb bkc bke bkk bkn bkr bnb bnc bne bnk bnn bnr brb bre brk brn brr c-- cbb cbc cbe cbk cbn cbr ccb ccc cce cck ccn ccr ce- ceb cec cee cek cen cer ckb ckc cn- cnb cnc cne cnn cnr crb crc cre crk crn crr ebb ebc ebe ebk ebn ebr ec- ecb ecc ece eck ecn ecr eeb eec eee eek een eer ekb ekc eke ekr en- enb enc ene enk enn enr erb erc ere erk ern err kbb kbc kbe kbk kbn kbr kcb kcc kce kck kcn kcr ke- keb kec kee kek ken ker kkb kkc kke kkk kkn kkr kn- knc kne knk knn knr krc krk krn krr nbb nbc nbe nbk nbn nbr ncb ncc nce nck ncn ncr ne- neb nec nee nek nen ner nkc nke nkk nkn nkr nnb nnc nne nnk nnn nrb nrc nre nrk nrn nrr rbb rbc rbe rbk rbn rbr rcb rcc rce rcn rcr re- reb rec ree rek ren rer rkb rkc rke rkk rnb rnc rnn rnr rrb rrc rrk rrn rrr