fff ffn ffo ffr fft fnf fnn fnr fnt fof fon foo for fot frf frn fro frr frt ftf ftn fto ftr ftt nff nfn nfo nfr nft nnf nnn nno nnt no- nof non noo nor not nrf nrn nro nrr nrt ntf ntn nto ntr ntt of- off ofn ofo ofr oft on- onf onn ono onr ont oo- oof oon ooo oor oot or- orf orn oro orr ort ot- otf otn oto otr ott rff rfn rfo rfr rft rnn rno rnr rnt rof ron roo ror rot rrf rrn rrr rrt rtf rtn rto rtr rtt tff tfn tfo tfr tft tnf tnn tno tnr tnt to- tof ton too tor tot trf trn tro trr trt ttf ttn tto ttr ttt