fff ffm ffo ffr ffs fmf fmm fmo fmr fms fof fom foo for fos frf frm fro frr frs fsf fsm fso fsr fss m-f m-o m-r mff mfm mfo mfr mfs mmf mmm mmo mmr mms mof mom moo mor mos mrf mrm mro mrr mrs msf msm mso msr mss of- off ofm ofo ofr ofs om- omf omm omo omr oms oo- oof oom ooo oor oos or- orf orm oro orr ors os- osf osm oso osr oss rff rfm rfo rfr rfs rmf rmm rmo rmr rms rof rom roo ror ros rrf rrm rrr rrs rsf rsm rso rsr rss sff sfm sfo sfr sfs smf smm smo smr sms sof som soo sor sos sr- srf srm sro srr srs ss- ssf ssm sso ssr sss