-er b-u bbb bbc bbe bbk bbo bbr bbt bbu bbx bcb bcc bce bck bco bcr bct bcu bcx be- beb bec bee bek beo ber bet beu bex bkb bkc bke bkk bko bkr bkt bkx bob boc boe bok boo bor bot bou box brb bre brk bro brr brt bru brx btb btc bte btk bto btr btt btu btx bub buc bue buk buo bur but buu bux bxb bxo bxx c-- cbb cbc cbe cbk cbo cbr cbt cbu cbx ccb ccc cce cck cco ccr cct ccu ccx ce- ceb cec cee cek ceo cer cet ceu cex ckb ckc cko ckt ckx co- cob coc coe cok coo cor cot cou cox crb crc cre crk cro crr crt cru crx ctb ctc cte ctk cto ctr ctt ctu ctx cub cuc cue cuk cuo cur cut cuu cxc cxk cxo cxr cxt cxx ebb ebc ebe ebk ebo ebr ebt ebu ebx ec- ecb ecc ece eck eco ecr ect ecu ecx eeb eec eee eek eeo eer eet eex ekb ekc eke eko ekr ekt eku eo- eob eoc eoe eok eoo eor eot eou erb erc ere erk ero err ert eru etb etc ete etk eto etr ett etu etx eu- eub euc eue eur eut eux ex- exc exe exo exr ext exu exx k-t kbb kbc kbe kbk kbo kbr kbu kbx kcb kcc kce kck kcr kct kcu kcx ke- keb kec kee kek keo ker ket kex kkb kkc kke kkk kkr kkt kku kob koc koe kok koo kor kot kou krc krk kro krr krt kru ktb ktc kte ktk kto ktr ktt ktu kub kuc kue kuk kur kut kuu kxo ob- obb obc obe obk obo obr obt obu obx oc- ocb occ ock oco ocr oct ocu ocx oeb oec oee oeo oer oet oex okb okc oke okk oko okr oku oo- oob ooc ook ooo oor oot oox or- orb orc ore ork oro orr ort oru orx ot- otb otc ote otk oto otr ott otu ou- ouc oue ouk ouo our out ox- oxb oxc oxo oxt oxx rbb rbc rbe rbk rbo rbr rbt rbu rbx rcb rcc rce rco rcr rct rcu rcx re- reb rec ree rek reo rer ret reu rex rkb rkc rke rkk rko rkt rku rob roc roe rok roo ror rot rou rox rrb rrc rrk rrr rrt rru rtb rtc rte rtk rto rtr rtt rtu rtx rub ruc rue ruk ruo rur rut ruu rux rxr t-x tbb tbc tbe tbk tbo tbr tbt tbu tcb tcc tce tck tco tcr tct tcu tcx te- teb tec tee tek teo ter tet teu tex tkb tkc tke tkk tko tkr tkt to- tob toc toe tok too tor tot tou tox trb trc tre trk tro trr trt tru trx ttb ttc tte ttk tto ttr ttt ttu ttx tub tuc tue tuk tuo tur tut tuu tux txe txk txt txu ubb ubc ube ubk ubo ubr ubt ubu ubx ucb ucc uce uck uco ucr uct ucu ueb uec uee uer uet ukb ukc uke ukk ukr uku uob uoc uoe uok uoo uor uot uox ur- urb urc ure urk uro urr urt uru urx utb utc ute utk uto utr utt utu utx uuc uue uur uut uuu uxb uxc uxo uxr uxt uxu xbc xbe xbr xbx xcb xcr xcx xee xer xet xeu xex xkb xke xoc xok xoo xor xot xox xrc xrt xrx xtc xtr xtx xue xxo xxx