-er bbb bbc bbe bbl bbr bbx bcb bcc bce bcl bcr bcx be- beb bec bee bel ber bex blb blc ble bll blr blx brb bre brl brr brx bxb bxl bxx c-- cbb cbc cbe cbl cbr cbx ccb ccc cce ccl ccr ccx ce- ceb cec cee cel cer cex cl- clb clc cle cll clr clx crb crc cre crl crr crx cxc cxl cxr cxx ebb ebc ebe ebl ebr ebx ec- ecb ecc ece ecl ecr ecx eeb eec eee eel eer eex elb elc ele ell elr elx erb erc ere erl err ex- exc exe exl exr exx lbb lbc lbe lbl lbr lbx lcb lcc lce lcl lcr lcx leb lec lee lel ler lex llb llc lle lll llr lrb lrc lrr lxc lxr lxx rbb rbc rbe rbl rbr rbx rcb rcc rce rcl rcr rcx re- reb rec ree rel rer rex rlc rle rll rlr rrb rrc rrl rrr rxr xbc xbe xbl xbr xbx xcb xcl xcr xcx xee xel xer xex xlb xlr xrc xrx xxl xxx