-er bbb bbc bbe bbn bbo bbr bbt bcb bcc bce bcn bco bcr bct be- beb bec bee ben beo ber bet bnb bnc bne bnn bno bnr bnt bob boc boe bon boo bor bot brb bre brn bro brr brt btb btc bte btn bto btr btt c-- cbb cbc cbe cbn cbo cbr cbt ccb ccc cce ccn cco ccr cct ce- ceb cec cee cen ceo cer cet cn- cnb cnc cne cnn cno cnr cnt co- cob coc coe con coo cor cot crb crc cre crn cro crr crt ctb ctc cte ctn cto ctr ctt ebb ebc ebe ebn ebo ebr ebt ec- ecb ecc ece ecn eco ecr ect eeb eec eee een eeo eer eet en- enb enc ene enn eno enr ent eo- eob eoc eoe eon eoo eor eot erb erc ere ern ero err ert etb etc ete etn eto etr ett nbb nbc nbe nbn nbo nbr nbt ncb ncc nce ncn nco ncr nct ne- neb nec nee nen neo ner net nnb nnc nne nnn nno nnt no- nob noc noe non noo nor not nrb nrc nre nrn nro nrr nrt ntb ntc nte ntn nto ntr ntt ob- obb obc obe obn obo obr obt oc- ocb occ ocn oco ocr oct oeb oec oee oen oeo oer oet on- onb onc one onn ono onr ont oo- oob ooc oon ooo oor oot or- orb orc ore orn oro orr ort ot- otb otc ote otn oto otr ott rbb rbc rbe rbn rbo rbr rbt rcb rcc rce rcn rco rcr rct re- reb rec ree ren reo rer ret rnb rnc rnn rno rnr rnt rob roc roe ron roo ror rot rrb rrc rrn rrr rrt rtb rtc rte rtn rto rtr rtt tbb tbc tbe tbn tbo tbr tbt tcb tcc tce tcn tco tcr tct te- teb tec tee ten teo ter tet tnb tnc tne tnn tno tnr tnt to- tob toc toe ton too tor tot trb trc tre trn tro trr trt ttb ttc tte ttn tto ttr ttt