bbb bbc bbe bbk bbn bbo bbt bcb bcc bce bck bcn bco bct be- beb bec bee bek ben beo bet bkb bkc bke bkk bkn bko bkt bnb bnc bne bnk bnn bno bnt bob boc boe bok bon boo bot btb btc bte btk btn bto btt c-- cbb cbc cbe cbk cbn cbo cbt ccb ccc cce cck ccn cco cct ce- ceb cec cee cek cen ceo cet ckb ckc cko ckt cn- cnb cnc cne cnn cno cnt co- cob coc coe cok con coo cot ctb ctc cte ctk ctn cto ctt ebb ebc ebe ebk ebn ebo ebt ec- ecb ecc ece eck ecn eco ect eeb eec eee eek een eeo eet ekb ekc eke eko ekt en- enb enc ene enk enn eno ent eo- eob eoc eoe eok eon eoo eot etb etc ete etk etn eto ett k-t kbb kbc kbe kbk kbn kbo kcb kcc kce kck kcn kct ke- keb kec kee kek ken keo ket kkb kkc kke kkk kkn kkt kn- knc kne knk knn kno knt kob koc koe kok kon koo kot ktb ktc kte ktk ktn kto ktt nbb nbc nbe nbk nbn nbo nbt ncb ncc nce nck ncn nco nct ne- neb nec nee nek nen neo net nkc nke nkk nkn nko nkt nnb nnc nne nnk nnn nno nnt no- nob noc noe nok non noo not ntb ntc nte ntk ntn nto ntt ob- obb obc obe obk obn obo obt oc- ocb occ ock ocn oco oct oeb oec oee oen oeo oet okb okc oke okk oko on- onb onc one onk onn ono ont oo- oob ooc ook oon ooo oot ot- otb otc ote otk otn oto ott tbb tbc tbe tbk tbn tbo tbt tcb tcc tce tck tcn tco tct te- teb tec tee tek ten teo tet tkb tkc tke tkk tko tkt tnb tnc tne tnk tnn tno tnt to- tob toc toe tok ton too tot ttb ttc tte ttk ttn tto ttt