fff ffm ffo ffs fft fmf fmm fmo fms fmt fof fom foo fos fot fsf fsm fso fss fst ftf ftm fto fts ftt m-f m-o mff mfm mfo mfs mft mmf mmm mmo mms mmt mof mom moo mos mot msf msm mso mss mst mtf mtm mto mts mtt of- off ofm ofo ofs oft om- omf omm omo oms omt oo- oof oom ooo oos oot os- osf osm oso oss ost ot- otf otm oto ots ott sff sfm sfo sfs sft smf smm smo sms smt sof som soo sos sot ss- ssf ssm sso sss sst stf stm sto sts stt tff tfm tfo tfs tft tmf tmm tmo tms tmt to- tof tom too tos tot tsf tsm tso tss tst ttf ttm tto tts ttt