-er bbb bbe bbh bbo bbr bbx be- beb bee beh beo ber bex bhb bhe bhh bho bhr bhx bob boe boh boo bor box brb bre brh bro brr brx bxb bxo bxx ebb ebe ebh ebo ebr ebx eeb eee eeo eer eex ehb ehe ehh eho ehr eo- eob eoe eoh eoo eor erb ere erh ero err ex- exe exh exo exr exx hbb hbe hbh hbo hbr hbx he- heb hee heh heo her hex hhb hhe hhh hho hhr hob hoe hoh hoo hor hox hr- hrb hre hrh hro hrr ob- obb obe obh obo obr obx oeb oee oeh oeo oer oex ohe ohh oho ohr oo- oob ooh ooo oor oox or- orb ore orh oro orr orx ox- oxb oxo oxx rbb rbe rbh rbo rbr rbx re- reb ree reh reo rer rex rh- rhb rhe rhh rho rhr rob roe roh roo ror rox rrb rrh rrr rxr xbe xbr xbx xee xer xex xoo xor xox xrx xxo xxx