bbb bbc bbm bbo bbt bcb bcc bcm bco bct bmb bmc bmm bmo bmt bob boc bom boo bot btb btc btm bto btt c-- cbb cbc cbm cbo cbt ccb ccc ccm cco cct cmb cmc cmm cmo cmt co- cob coc com coo cot ctb ctc ctm cto ctt m-o mbb mbc mbm mbo mbt mc- mcb mcc mcm mco mct mmb mmc mmm mmo mmt mob moc mom moo mot mtb mtc mtm mto mtt ob- obb obc obm obo obt oc- ocb occ ocm oco oct om- omb omc omm omo omt oo- oob ooc oom ooo oot ot- otb otc otm oto ott tbb tbc tbm tbo tbt tcb tcc tcm tco tct tmb tmc tmm tmo tmt to- tob toc tom too tot ttb ttc ttm tto ttt