fff ffn ffr ffs fft fnf fnn fnr fns fnt frf frn frr frs frt fsf fsn fsr fss fst ftf ftn ftr fts ftt nff nfn nfr nfs nft nnf nnn nns nnt nrf nrn nrr nrs nrt nsf nsn nsr nss nst ntf ntn ntr nts ntt rff rfn rfr rfs rft rnn rnr rns rnt rrf rrn rrr rrs rrt rsf rsn rsr rss rst rtf rtn rtr rts rtt sff sfn sfr sfs sft snf snn snr sns snt sr- srf srn srr srs srt ss- ssf ssn ssr sss sst stf stn str sts stt tff tfn tfr tfs tft tnf tnn tnr tns tnt trf trn trr trs trt tsf tsn tsr tss tst ttf ttn ttr tts ttt