fff ffi ffm ffs ffx fif fii fim fis fix fmf fmi fmm fms fmx fsf fsi fsm fss fsx fxi fxm fxs fxx i-f iff ifi ifm ifs ifx iif iii iim iis iix im- imf imi imm ims imx is- isf isi ism iss ixi m-f mff mfi mfm mfs mi- mif mii mim mis mix mmf mmi mmm mms mmx msf msi msm mss msx mxi mxs sff sfi sfm sfs sfx sif sii sim sis six smf smi smm sms smx ss- ssf ssi ssm sss ssx sxi sxm sxs xfm xfs xfx xii xis xix xmf xmi xmm xms xmx xsi xsm xss xxi xxx