bbb bbc bbe bbo bbs bcb bcc bce bco bcs be- beb bec bee beo bes bob boc boe boo bos bsb bsc bse bso bss c-- cbb cbc cbe cbo cbs ccb ccc cce cco ccs ce- ceb cec cee ceo ces co- cob coc coe coo cos csb csc cse cso css ebb ebc ebe ebo ebs ec- ecb ecc ece eco ecs eeb eec eee eeo ees eo- eob eoc eoe eoo eos es- esb esc ese eso ess ob- obb obc obe obo obs oc- ocb occ oco ocs oeb oec oee oeo oes oo- oob ooc ooo oos os- osb osc ose oso oss sbb sbc sbe sbo sbs scb scc sce sco scs se- seb sec see seo ses sob soc soe soo sos ss- ssb ssc sse sso sss