bbb bbc bbe bbk bbo bcb bcc bce bck bco bcv be- beb bec bee bek beo bev bkb bkc bke bkk bko bkv bob boc boe bok boo bov bvb bvc bve bvk bvo bvv c-- cbb cbc cbe cbk cbo cbv ccb ccc cce cck cco ccv ce- ceb cec cee cek ceo cev ckb ckc cko co- cob coc coe cok coo cov cvb cvc cve cvk cvo cvv ebb ebc ebe ebk ebo ebv ec- ecb ecc ece eck eco ecv eeb eec eee eek eeo eev ekb ekc eke eko ekv eo- eob eoc eoe eok eoo evb evc eve evo evv kbb kbc kbe kbk kbo kcb kcc kce kck ke- keb kec kee kek keo kev kkb kkc kke kkk kkv kob koc koe kok koo kvb kvk kvo kvv ob- obb obc obe obk obo obv oc- ocb occ ock oco ocv oeb oec oee oeo okb okc oke okk oko oo- oob ooc ook ooo oov ov- ovb ovc ove ovo ovv v-e vbc vbk vbo vbv vcc vce vco veb vec vee vek veo vkb vob voc voe vok voo vov vvb vvc vvo vvv