-er bbb bbc bbe bbg bbn bbo bbr bcb bcc bce bcg bcn bco bcr be- beb bec bee beg ben beo ber bgb bgc bge bgg bgn bgo bgr bnb bnc bne bng bnn bno bnr bob boc boe bog bon boo bor brb bre brg brn bro brr c-- cbb cbc cbe cbg cbn cbo cbr ccb ccc cce ccg ccn cco ccr ce- ceb cec cee ceg cen ceo cer cgb cgc cge cgg cgn cgo cgr cn- cnb cnc cne cng cnn cno cnr co- cob coc coe cog con coo cor crb crc cre crg crn cro crr ebb ebc ebe ebg ebn ebo ebr ec- ecb ecc ece ecg ecn eco ecr eeb eec eee eeg een eeo eer egb egc ege egg egn ego egr en- enb enc ene eng enn eno enr eo- eob eoc eoe eog eon eoo eor erb erc ere erg ern ero err gbc gbe gbg gbn gbo gbr gcb gcc gce gcg gcn gco gcr ge- geb gec gee geg gen geo ger ggb ggc ggg ggn ggo ggr gnb gnc gne gnn gno gnr gob goc goe gog gon goo gor grb grc gre grg grn gro grr nbb nbc nbe nbg nbn nbo nbr ncb ncc nce ncg ncn nco ncr ne- neb nec nee neg nen neo ner ngb ngc nge ngg ngn ngo nnb nnc nne nng nnn nno no- nob noc noe nog non noo nor nrb nrc nre nrg nrn nro nrr ob- obb obc obe obg obn obo obr oc- ocb occ ocg ocn oco ocr oeb oec oee oeg oen oeo oer ogc oge ogg ogn ogo on- onb onc one ong onn ono onr oo- oob ooc oog oon ooo oor or- orb orc ore org orn oro orr rbb rbc rbe rbg rbn rbo rbr rcb rcc rce rcg rcn rco rcr re- reb rec ree reg ren reo rer rgb rgc rge rgg rgn rgo rgr rnb rnc rng rnn rno rnr rob roc roe rog ron roo ror rrb rrc rrg rrn rrr