-er bbb bbe bbk bbr bbt be- beb bee bek ber bet bkb bke bkk bkr bkt brb bre brk brr brt btb bte btk btr btt ebb ebe ebk ebr ebt eeb eee eek eer eet ekb eke ekr ekt erb ere erk err ert etb ete etk etr ett k-t kbb kbe kbk kbr ke- keb kee kek ker ket kkb kke kkk kkr kkt krk krr krt ktb kte ktk ktr ktt rbb rbe rbk rbr rbt re- reb ree rek rer ret rkb rke rkk rkt rrb rrk rrr rrt rtb rte rtk rtr rtt tbb tbe tbk tbr tbt te- teb tee tek ter tet tkb tke tkk tkr tkt trb tre trk trr trt ttb tte ttk ttr ttt