-er bbb bbe bbn bbo bbr bbt bbx be- beb bee ben beo ber bet bex bnb bne bnn bno bnr bnt bnx bob boe bon boo bor bot box brb bre brn bro brr brt brx btb bte btn bto btr btt btx bxb bxn bxo bxx ebb ebe ebn ebo ebr ebt ebx eeb eee een eeo eer eet eex en- enb ene enn eno enr ent eo- eob eoe eon eoo eor eot erb ere ern ero err ert etb ete etn eto etr ett etx ex- exe exo exr ext exx nbb nbe nbn nbo nbr nbt nbx ne- neb nee nen neo ner net nex nnb nne nnn nno nnt no- nob noe non noo nor not nox nrb nre nrn nro nrr nrt nrx ntb nte ntn nto ntr ntt ntx nxt ob- obb obe obn obo obr obt obx oeb oee oen oeo oer oet oex on- onb one onn ono onr ont onx oo- oob oon ooo oor oot oox or- orb ore orn oro orr ort orx ot- otb ote otn oto otr ott ox- oxb oxn oxo oxt oxx rbb rbe rbn rbo rbr rbt rbx re- reb ree ren reo rer ret rex rnb rnn rno rnr rnt rob roe ron roo ror rot rox rrb rrn rrr rrt rtb rte rtn rto rtr rtt rtx rxr t-x tbb tbe tbn tbo tbr tbt te- teb tee ten teo ter tet tex tnb tne tnn tno tnr tnt tnx to- tob toe ton too tor tot tox trb tre trn tro trr trt trx ttb tte ttn tto ttr ttt ttx txe txn txt xbe xbr xbx xee xen xer xet xex xno xon xoo xor xot xox xrt xrx xtr xtx xxo xxx