-er bbb bbe bbi bbk bbo bbr bbt be- beb bee bei bek beo ber bet bi- bib bie bii bik bio bir bit bkb bke bkk bko bkr bkt bob boe boi bok boo bor bot brb bre bri brk bro brr brt btb bte bti btk bto btr btt ebb ebe ebi ebk ebo ebr ebt eeb eee eek eeo eer eet eib eie eii eik eio eir eit ekb eke eki eko ekr ekt eo- eob eoe eoi eok eoo eor eot erb ere eri erk ero err ert etb ete eti etk eto etr ett ibb ibe ibi ibk ibo ibr ibt ie- iee iei iek ier iet iib iie iii iio iir iit ikb ike iki ikk iko ikr ikt io- iob ioe ioi ioo ior iot ir- irb ire iri irk iro irr irt itb ite iti itk ito itt k-t kbb kbe kbi kbk kbo kbr ke- keb kee kei kek keo ker ket kib kie kii kik kio kir kit kkb kke kki kkk kkr kkt kob koe koi kok koo kor kot kri krk kro krr krt ktb kte ktk kto ktr ktt o-i ob- obb obe obi obk obo obr obt oeb oee oei oeo oer oet oib oie oii oik oio oir oit okb oke oki okk oko okr oo- oob ooi ook ooo oor oot or- orb ore ori ork oro orr ort ot- otb ote oti otk oto otr ott rbb rbe rbi rbk rbo rbr rbt re- reb ree rei rek reo rer ret rib rie rii rik rio rir rit rkb rke rkk rko rkt rob roe roi rok roo ror rot rrb rri rrk rrr rrt rtb rte rti rtk rto rtr rtt tbb tbe tbi tbk tbo tbr tbt te- teb tee tei tek teo ter tet tib tie tii tik tio tir tit tkb tke tkk tko tkr tkt to- tob toe toi tok too tor tot trb tre tri trk tro trr trt ttb tte tti ttk tto ttr ttt