-er bbb bbc bbe bbh bbo bbr bbs bcb bcc bce bch bco bcr bcs be- beb bec bee beh beo ber bes bhb bhc bhe bhh bho bhr bhs bob boc boe boh boo bor bos brb bre brh bro brr brs bsb bsc bse bsh bso bsr bss c-- cbb cbc cbe cbh cbo cbr cbs ccb ccc cce cch cco ccr ccs ce- ceb cec cee ceh ceo cer ces ch- chb chc che chh cho chr chs co- cob coc coe coh coo cor cos crb crc cre crh cro crr crs csb csc cse csh cso csr css ebb ebc ebe ebh ebo ebr ebs ec- ecb ecc ece ech eco ecr ecs eeb eec eee eeo eer ees ehb ehc ehe ehh eho ehr ehs eo- eob eoc eoe eoh eoo eor eos erb erc ere erh ero err ers es- esb esc ese esh eso esr ess hbb hbc hbe hbh hbo hbr hbs hcb hcc hce hch hco hcr hcs he- heb hec hee heh heo her hes hhb hhc hhe hhh hho hhr hhs hob hoc hoe hoh hoo hor hos hr- hrb hrc hre hrh hro hrr hrs hsb hsc hse hsh hsr hss ob- obb obc obe obh obo obr obs oc- ocb occ och oco ocr ocs oeb oec oee oeh oeo oer oes ohc ohe ohh oho ohr ohs oo- oob ooc ooh ooo oor oos or- orb orc ore orh oro orr ors os- osb osc ose osh oso osr oss rbb rbc rbe rbh rbo rbr rbs rcb rcc rce rch rco rcr rcs re- reb rec ree reh reo rer res rh- rhb rhc rhe rhh rho rhr rhs rob roc roe roh roo ror ros rrb rrc rrh rrr rrs rsb rsc rse rsh rso rsr rss sbb sbc sbe sbh sbo sbr sbs scb scc sce sch sco scr scs se- seb sec see seh seo ser ses sh- shb shc she shh sho shr shs sob soc soe soh soo sor sos sr- srb src sre srh sro srr srs ss- ssb ssc sse ssh sso ssr sss