-er bbb bbc bbe bbn bbr bbs bbt bcb bcc bce bcn bcr bcs bct be- beb bec bee ben ber bes bet bnb bnc bne bnn bnr bns bnt brb bre brn brr brs brt bsb bsc bse bsn bsr bss bst btb btc bte btn btr bts btt c-- cbb cbc cbe cbn cbr cbs cbt ccb ccc cce ccn ccr ccs cct ce- ceb cec cee cen cer ces cet cn- cnb cnc cne cnn cnr cns cnt crb crc cre crn crr crs crt csb csc cse csn csr css cst ctb ctc cte ctn ctr cts ctt ebb ebc ebe ebn ebr ebs ebt ec- ecb ecc ece ecn ecr ecs ect eeb eec eee een eer ees eet en- enb enc ene enn enr ens ent erb erc ere ern err ers ert es- esb esc ese esn esr ess est etb etc ete etn etr ets ett nbb nbc nbe nbn nbr nbs nbt ncb ncc nce ncn ncr ncs nct ne- neb nec nee nen ner nes net nnb nnc nne nnn nns nnt nrb nrc nre nrn nrr nrs nrt nsb nsc nse nsn nsr nss nst ntb ntc nte ntn ntr nts ntt rbb rbc rbe rbn rbr rbs rbt rcb rcc rce rcn rcr rcs rct re- reb rec ree ren rer res ret rnb rnc rnn rnr rns rnt rrb rrc rrn rrr rrs rrt rsb rsc rse rsn rsr rss rst rtb rtc rte rtn rtr rts rtt sbb sbc sbe sbn sbr sbs sbt scb scc sce scn scr scs sct se- seb sec see sen ser ses set snb snc sne snn snr sns snt sr- srb src sre srn srr srs srt ss- ssb ssc sse ssn ssr sss sst stb stc ste stn str sts stt tbb tbc tbe tbn tbr tbs tbt tcb tcc tce tcn tcr tcs tct te- teb tec tee ten ter tes tet tnb tnc tne tnn tnr tns tnt trb trc tre trn trr trs trt tsb tsc tse tsn tsr tss tst ttb ttc tte ttn ttr tts ttt