-er bbb bbe bbn bbo bbr be- beb bee ben beo ber bnb bne bnn bno bnr bob boe bon boo bor brb bre brn bro brr ebb ebe ebn ebo ebr eeb eee een eeo eer en- enb ene enn eno enr eo- eob eoe eon eoo eor erb ere ern ero err nbb nbe nbn nbo nbr ne- neb nee nen neo ner nnb nne nnn nno no- nob noe non noo nor nrb nre nrn nro nrr ob- obb obe obn obo obr oeb oee oen oeo oer on- onb one onn ono onr oo- oob oon ooo oor or- orb ore orn oro orr rbb rbe rbn rbo rbr re- reb ree ren reo rer rnb rnn rno rnr rob roe ron roo ror rrb rrn rrr