-er bbb bbc bbe bbk bbr bcb bcc bce bck bcr bcz be- beb bec bee bek ber bez bkb bkc bke bkk bkr brb bre brk brr brz bze bzr bzz c-- cbb cbc cbe cbk cbr cbz ccb ccc cce cck ccr ccz ce- ceb cec cee cek cer cez ckb ckc crb crc cre crk crr crz cz- czc cze czk ebb ebc ebe ebk ebr ec- ecb ecc ece eck ecr eeb eec eee eek eer ekb ekc eke ekr erb erc ere erk err erz eze ezr ezz k-z kbb kbc kbe kbk kbr kbz kcb kcc kce kck kcr ke- keb kec kee kek ker kez kkb kkc kke kkk kkr krc krk krr rbb rbc rbe rbk rbr rcb rcc rce rcr re- reb rec ree rek rer rez rkb rkc rke rkk rkz rrb rrc rrk rrr rzb rze zbb zbc zbr zce zeb zec zee zek zer zez zzr zzz