-er bbb bbc bbe bbr bbt bcb bcc bce bcr bct bcz be- beb bec bee ber bet bez brb bre brr brt brz btb btc bte btr btt btz bze bzr bzz c-- cbb cbc cbe cbr cbt cbz ccb ccc cce ccr cct ccz ce- ceb cec cee cer cet cez crb crc cre crr crt crz ctb ctc cte ctr ctt ctz cz- czc cze czt ebb ebc ebe ebr ebt ec- ecb ecc ece ecr ect eeb eec eee eer eet erb erc ere err ert erz etb etc ete etr ett etz eze ezr ezz rbb rbc rbe rbr rbt rcb rcc rce rcr rct re- reb rec ree rer ret rez rrb rrc rrr rrt rtb rtc rte rtr rtt rtz rzb rze tbb tbc tbe tbr tbt tbz tcb tcc tce tcr tct te- teb tec tee ter tet tez trb trc tre trr trt trz ttb ttc tte ttr ttt tze zbb zbc zbr zbt zce zeb zec zee zer zet zez zte ztr zzr zzt zzz