bbb bbc bbe bbn bbo bcb bcc bce bcn bco be- beb bec bee ben beo bnb bnc bne bnn bno bob boc boe bon boo c-- cbb cbc cbe cbn cbo ccb ccc cce ccn cco ce- ceb cec cee cen ceo cn- cnb cnc cne cnn cno co- cob coc coe con coo ebb ebc ebe ebn ebo ec- ecb ecc ece ecn eco eeb eec eee een eeo en- enb enc ene enn eno eo- eob eoc eoe eon eoo nbb nbc nbe nbn nbo ncb ncc nce ncn nco ne- neb nec nee nen neo nnb nnc nne nnn nno no- nob noc noe non noo ob- obb obc obe obn obo oc- ocb occ ocn oco oeb oec oee oen oeo on- onb onc one onn ono oo- oob ooc oon ooo