-er b-u bbb bbe bbo bbr bbt bbu be- beb bee beo ber bet beu bob boe boo bor bot bou brb bre bro brr brt bru btb bte bto btr btt btu bub bue buo bur but buu ebb ebe ebo ebr ebt ebu eeb eee eeo eer eet eo- eob eoe eoo eor eot eou erb ere ero err ert eru etb ete eto etr ett etu eu- eub eue eur eut ob- obb obe obo obr obt obu oeb oee oeo oer oet oo- oob ooo oor oot or- orb ore oro orr ort oru ot- otb ote oto otr ott otu ou- oue ouo our out rbb rbe rbo rbr rbt rbu re- reb ree reo rer ret reu rob roe roo ror rot rou rrb rrr rrt rru rtb rte rto rtr rtt rtu rub rue ruo rur rut ruu tbb tbe tbo tbr tbt tbu te- teb tee teo ter tet teu to- tob toe too tor tot tou trb tre tro trr trt tru ttb tte tto ttr ttt ttu tub tue tuo tur tut tuu ubb ube ubo ubr ubt ubu ueb uee uer uet uob uoe uoo uor uot ur- urb ure uro urr urt uru utb ute uto utr utt utu uue uur uut uuu