-er bbb bbc bbe bbh bbk bbo bbr bcb bcc bce bch bck bco bcr be- beb bec bee beh bek beo ber bhb bhc bhe bhh bhk bho bhr bkb bkc bke bkk bko bkr bob boc boe boh bok boo bor brb bre brh brk bro brr c-- cbb cbc cbe cbh cbk cbo cbr ccb ccc cce cch cck cco ccr ce- ceb cec cee ceh cek ceo cer ch- chb chc che chh chk cho chr ckb ckc ckh cko co- cob coc coe coh cok coo cor crb crc cre crh crk cro crr ebb ebc ebe ebh ebk ebo ebr ec- ecb ecc ece ech eck eco ecr eeb eec eee eek eeo eer ehb ehc ehe ehh eho ehr ekb ekc eke ekh eko ekr eo- eob eoc eoe eoh eok eoo eor erb erc ere erh erk ero err hbb hbc hbe hbh hbk hbo hbr hcb hcc hce hch hck hco hcr he- heb hec hee heh hek heo her hhb hhc hhe hhh hhk hho hhr hkb hkh hkk hko hkr hob hoc hoe hoh hok hoo hor hr- hrb hrc hre hrh hrk hro hrr kbb kbc kbe kbh kbk kbo kbr kcb kcc kce kch kck kcr ke- keb kec kee keh kek keo ker khe khh khk kho khr kkb kkc kke kkh kkk kkr kob koc koe koh kok koo kor krc krk kro krr ob- obb obc obe obh obk obo obr oc- ocb occ och ock oco ocr oeb oec oee oeh oeo oer ohc ohe ohh oho ohr okb okc oke okk oko okr oo- oob ooc ooh ook ooo oor or- orb orc ore orh ork oro orr rbb rbc rbe rbh rbk rbo rbr rcb rcc rce rch rco rcr re- reb rec ree reh rek reo rer rh- rhb rhc rhe rhh rho rhr rkb rkc rke rkk rko rob roc roe roh rok roo ror rrb rrc rrh rrk rrr