fff ffn ffo fft ffx fnf fnn fnt fnx fof fon foo fot fox ftf ftn fto ftt ftx fxt fxx nff nfn nfo nft nnf nnn nno nnt no- nof non noo not nox ntf ntn nto ntt ntx nxt of- off ofn ofo oft ofx on- onf onn ono ont onx oo- oof oon ooo oot oox ot- otf otn oto ott ox- oxf oxn oxo oxt oxx t-x tff tfn tfo tft tfx tnf tnn tno tnt tnx to- tof ton too tot tox ttf ttn tto ttt ttx txf txn txt xfn xft xfx xno xof xon xoo xot xox xtf xtx xxo xxx