-er bbb bbc bbe bbn bbr bbt bcb bcc bce bcn bcr bct be- beb bec bee ben ber bet bnb bnc bne bnn bnr bnt brb bre brn brr brt btb btc bte btn btr btt c-- cbb cbc cbe cbn cbr cbt ccb ccc cce ccn ccr cct ce- ceb cec cee cen cer cet cn- cnb cnc cne cnn cnr cnt crb crc cre crn crr crt ctb ctc cte ctn ctr ctt ebb ebc ebe ebn ebr ebt ec- ecb ecc ece ecn ecr ect eeb eec eee een eer eet en- enb enc ene enn enr ent erb erc ere ern err ert etb etc ete etn etr ett nbb nbc nbe nbn nbr nbt ncb ncc nce ncn ncr nct ne- neb nec nee nen ner net nnb nnc nne nnn nnt nrb nrc nre nrn nrr nrt ntb ntc nte ntn ntr ntt rbb rbc rbe rbn rbr rbt rcb rcc rce rcn rcr rct re- reb rec ree ren rer ret rnb rnc rnn rnr rnt rrb rrc rrn rrr rrt rtb rtc rte rtn rtr rtt tbb tbc tbe tbn tbr tbt tcb tcc tce tcn tcr tct te- teb tec tee ten ter tet tnb tnc tne tnn tnr tnt trb trc tre trn trr trt ttb ttc tte ttn ttr ttt