fff ffi ffm ffo ffs fif fii fim fis fmf fmi fmm fmo fms fof foi fom foo fos fsf fsi fsm fso fss i-f iff ifi ifm ifo ifs iif iii iim iio iis im- imf imi imm imo ims io- iof ioi iom ioo ios is- isf isi ism iso iss m-f m-o mff mfi mfm mfo mfs mi- mif mii mim mio mis mmf mmi mmm mmo mms mof moi mom moo mos msf msi msm mso mss o-i of- off ofi ofm ofo ofs oif oii oim oio ois om- omf omi omm omo oms oo- oof ooi oom ooo oos os- osf osi osm oso oss sff sfi sfm sfo sfs sif sii sim sio sis smf smi smm smo sms sof soi som soo sos ss- ssf ssi ssm sso sss