-er bbb bbc bbe bbm bbr bbt bcb bcc bce bcm bcr bct be- beb bec bee bem ber bet bmb bmc bme bmm bmr bmt brb bre brm brr brt btb btc bte btm btr btt c-- cbb cbc cbe cbm cbr cbt ccb ccc cce ccm ccr cct ce- ceb cec cee cem cer cet cmb cmc cme cmm cmr cmt crb crc cre crm crr crt ctb ctc cte ctm ctr ctt ebb ebc ebe ebm ebr ebt ec- ecb ecc ece ecm ecr ect eeb eec eee eem eer eet em- emb emc eme emm emr emt erb erc ere erm err ert etb etc ete etm etr ett m-r mbb mbc mbe mbm mbr mbt mc- mcb mcc mce mcm mcr mct meb mec mee mem mer met mmb mmc mme mmm mmr mmt mrb mrc mre mrm mrr mrt mtb mtc mte mtm mtr mtt rbb rbc rbe rbm rbr rbt rcb rcc rce rcm rcr rct re- reb rec ree rem rer ret rmb rmc rme rmm rmr rmt rrb rrc rrm rrr rrt rtb rtc rte rtm rtr rtt tbb tbc tbe tbm tbr tbt tcb tcc tce tcm tcr tct te- teb tec tee tem ter tet tmb tmc tme tmm tmr tmt trb trc tre trm trr trt ttb ttc tte ttm ttr ttt