-er bbb bbc bbe bbl bbr bbt bcb bcc bce bcl bcr bct be- beb bec bee bel ber bet blb blc ble bll blr blt brb bre brl brr brt btb btc bte btl btr btt c-- cbb cbc cbe cbl cbr cbt ccb ccc cce ccl ccr cct ce- ceb cec cee cel cer cet cl- clb clc cle cll clr clt crb crc cre crl crr crt ctb ctc cte ctl ctr ctt ebb ebc ebe ebl ebr ebt ec- ecb ecc ece ecl ecr ect eeb eec eee eel eer eet elb elc ele ell elr elt erb erc ere erl err ert etb etc ete etl etr ett lbb lbc lbe lbl lbr lbt lcb lcc lce lcl lcr lct leb lec lee lel ler let llb llc lle lll llr llt lrb lrc lrr lrt ltb ltc lte ltl ltr ltt rbb rbc rbe rbl rbr rbt rcb rcc rce rcl rcr rct re- reb rec ree rel rer ret rlc rle rll rlr rlt rrb rrc rrl rrr rrt rtb rtc rte rtl rtr rtt tbb tbc tbe tbl tbr tbt tcb tcc tce tcl tcr tct te- teb tec tee tel ter tet tlc tle tll tlr tlt trb trc tre trl trr trt ttb ttc tte ttl ttr ttt