fff ffg ffo ffs fft fgf fgg fgs fgt fof fog foo fos fot fsf fsg fso fss fst ftf ftg fto fts ftt gff gfo gfs gft ggg ggo ggs ggt gof gog goo gos got gsf gsg gso gss gst gtf gtg gto gts gtt of- off ofg ofo ofs oft ogf ogg ogo ogs ogt oo- oof oog ooo oos oot os- osf osg oso oss ost ot- otf otg oto ots ott sff sfg sfo sfs sft sgf sgg sgo sgs sgt sof sog soo sos sot ss- ssf ssg sso sss sst stf stg sto sts stt tff tfg tfo tfs tft tgf tgg tgo tgs tgt to- tof tog too tos tot tsf tsg tso tss tst ttf ttg tto tts ttt