bbb bbc bbf bbg bbo bbt bcb bcc bcf bcg bco bct bfb bfc bff bfg bfo bft bgb bgc bgf bgg bgo bgt bob boc bof bog boo bot btb btc btf btg bto btt c-- cbb cbc cbf cbg cbo cbt ccb ccc ccf ccg cco cct cfb cfc cff cfg cfo cft cgb cgc cgg cgo cgt co- cob coc cof cog coo cot ctb ctc ctf ctg cto ctt fbb fbc fbf fbg fbo fbt fcb fcc fcf fcg fco fct ffc fff ffg ffo fft fgb fgc fgf fgg fgt fob foc fof fog foo fot ftb ftc ftf ftg fto ftt gbc gbf gbg gbo gbt gcb gcc gcf gcg gco gct gfb gfc gff gfo gft ggb ggc ggg ggo ggt gob goc gof gog goo got gtb gtc gtf gtg gto gtt ob- obb obc obf obg obo obt oc- ocb occ ocf ocg oco oct of- ofb ofc off ofg ofo oft ogc ogf ogg ogo ogt oo- oob ooc oof oog ooo oot ot- otb otc otf otg oto ott tbb tbc tbf tbg tbo tbt tcb tcc tcf tcg tco tct tfb tfc tff tfg tfo tft tgb tgc tgf tgg tgo tgt to- tob toc tof tog too tot ttb ttc ttf ttg tto ttt