-er bbb bbe bbm bbr bbt bbx be- beb bee bem ber bet bex bmb bme bmm bmr bmt bmx brb bre brm brr brt brx btb bte btm btr btt btx bxb bxm bxx ebb ebe ebm ebr ebt ebx eeb eee eem eer eet eex em- emb eme emm emr emt emx erb ere erm err ert etb ete etm etr ett etx ex- exe exr ext exx m-r mbb mbe mbm mbr mbt mbx meb mee mem mer met mex mmb mme mmm mmr mmt mmx mrb mre mrm mrr mrt mrx mtb mte mtm mtr mtt mtx mxr rbb rbe rbm rbr rbt rbx re- reb ree rem rer ret rex rmb rme rmm rmr rmt rmx rrb rrm rrr rrt rtb rte rtm rtr rtt rtx rxr t-x tbb tbe tbm tbr tbt te- teb tee tem ter tet tex tmb tme tmm tmr tmt tmx trb tre trm trr trt trx ttb tte ttm ttr ttt ttx txe txt xbe xbr xbx xee xem xer xet xex xmm xmr xmt xmx xrt xrx xtm xtr xtx xxx