fff ffo ffp ffr ffs fft ffx fof foo fop for fos fot fox fpo fpp fpr fps fpt fpx frf fro frp frr frs frt fsf fso fsp fsr fss fst fsx ftf fto ftp ftr fts ftt ftx fxp fxr fxs fxt fxx of- off ofo ofp ofr ofs oft ofx oo- oof ooo oop oor oos oot oox op- opf opo opp opr ops opt opx or- orf oro orp orr ors ort orx os- osf oso osp osr oss ost osx ot- otf oto otp otr ots ott ox- oxf oxo oxt oxx p-p pff pfo pfp pfr pfs pft pfx pof poo pop por pos pot pox ppf ppo ppp ppr pps ppt ppx prf pro prp prr prs prt prx ps- psf pso psp psr pss pst psx pt- ptf pto ptp ptr pts ptt ptx pxr pxs pxt rff rfo rfp rfr rfs rft rof roo rop ror ros rot rox rpf rpo rpp rpr rps rpt rpx rrf rrp rrr rrs rrt rsf rso rsp rsr rss rst rsx rtf rto rtp rtr rts rtt rtx rxp rxr rxs sff sfo sfp sfr sfs sft sfx sof soo sop sor sos sot sox spf spo spp spr sps spt spx sr- srf sro srp srr srs srt srx ss- ssf sso ssp ssr sss sst ssx stf sto stp str sts stt stx sxs sxt t-x tff tfo tfp tfr tfs tft tfx to- tof too top tor tos tot tox tpf tpo tpp tpr tps tpt tpx trf tro trp trr trs trt trx tsf tso tsp tsr tss tst tsx ttf tto ttp ttr tts ttt ttx txf txs txt xfs xft xfx xof xoo xop xor xos xot xox xpf xpo xpp xps xpt xrf xrt xrx xsp xss xst xtf xtp xtr xts xtx xxo xxp xxx