-er bbb bbc bbe bbk bbl bbr bcb bcc bce bck bcl bcr be- beb bec bee bek bel ber bkb bkc bke bkk bkl bkr blb blc ble blk bll blr brb bre brk brl brr c-- cbb cbc cbe cbk cbl cbr ccb ccc cce cck ccl ccr ce- ceb cec cee cek cel cer ckb ckc cl- clb clc cle clk cll clr crb crc cre crk crl crr ebb ebc ebe ebk ebl ebr ec- ecb ecc ece eck ecl ecr eeb eec eee eek eel eer ekb ekc eke ekl ekr elb elc ele elk ell elr erb erc ere erk erl err kbb kbc kbe kbk kbl kbr kcb kcc kce kck kcl kcr ke- keb kec kee kek kel ker kkb kkc kke kkk kkl kkr kl- klb klc klr krc krk krl krr lbb lbc lbe lbk lbl lbr lcb lcc lce lck lcl lcr leb lec lee lek lel ler lkb lkl lkr llb llc lle llk lll llr lrb lrc lrk lrr rbb rbc rbe rbk rbl rbr rcb rcc rce rcl rcr re- reb rec ree rek rel rer rkb rkc rke rkk rlc rle rll rlr rrb rrc rrk rrl rrr