-er bbb bbe bbg bbo bbr be- beb bee beg beo ber bez bgb bge bgg bgo bgr bgz bob boe bog boo bor boz brb bre brg bro brr brz bze bzo bzr bzz ebb ebe ebg ebo ebr eeb eee eeg eeo eer egb ege egg ego egr eo- eob eoe eog eoo eor erb ere erg ero err erz eze ezo ezr ezz gbe gbg gbo gbr gbz ge- geb gee geg geo ger gez ggb ggg ggo ggr ggz gob goe gog goo gor goz grb gre grg gro grr gzo gzr ob- obb obe obg obo obr oeb oee oeg oeo oer oge ogg ogo oo- oob oog ooo oor or- orb ore org oro orr orz oze ozo ozz rbb rbe rbg rbo rbr re- reb ree reg reo rer rez rgb rge rgg rgo rgr rob roe rog roo ror roz rrb rrg rrr rzb rze rzo z-g zbb zbr zeb zee zeo zer zez zgb zgg zo- zob zoe zog zoo zor zro zzr zzz