-er bbb bbc bbd bbe bbk bbr bbs bcb bcc bcd bce bck bcr bcs bdb bdc bdd bde bdk bdr bds be- beb bec bed bee bek ber bes bkb bkc bke bkk bkr bks brb brd bre brk brr brs bsb bsc bsd bse bsk bsr bss c-- cbb cbc cbd cbe cbk cbr cbs ccb ccc ccd cce cck ccr ccs cdb cdc cdd cde cdk cdr cds ce- ceb cec ced cee cek cer ces ckb ckc ckd cks crb crc crd cre crk crr crs csb csc csd cse csk csr css dbb dbc dbd dbe dbk dbr dbs dcb dcc dcd dce dck dcr dcs ddb ddc ddd dde ddk ddr dds de- deb dec ded dee dek der des dkb dkc dke dkk dkr dks drb drc drd dre drk drr drs dsb dsc dsd dse dsk dsr dss ebb ebc ebd ebe ebk ebr ebs ec- ecb ecc ecd ece eck ecr ecs ed- edb edc edd ede edk edr eds eeb eec eed eee eek eer ees ekb ekc ekd eke ekr eks erb erc erd ere erk err ers es- esb esc esd ese esk esr ess kbb kbc kbd kbe kbk kbr kbs kcb kcc kcd kce kck kcr kcs kdb kdc kde kdk kdr kds ke- keb kec ked kee kek ker kes kkb kkc kke kkk kkr kks krc krd krk krr krs ksb ksc ksd kse ksk ksr kss rbb rbc rbd rbe rbk rbr rbs rcb rcc rcd rce rcr rcs rdb rdc rdd rde rdr rds re- reb rec red ree rek rer res rkb rkc rke rkk rks rrb rrc rrd rrk rrr rrs rsb rsc rsd rse rsk rsr rss sbb sbc sbd sbe sbk sbr sbs scb scc scd sce sck scr scs sdb sdc sdd sde sdk sdr sds se- seb sec sed see sek ser ses sk- skb skc skd ske skk skr sks sr- srb src srd sre srk srr srs ss- ssb ssc ssd sse ssk ssr sss