ddd ddf ddi ddt ddx dfd dff dfi dft dfx di- did dif dii dit dix dtd dtf dti dtt dtx dxd dxi dxt dxx fdd fdf fdi fdt fdx ffd fff ffi fft ffx fid fif fii fit fix ftd ftf fti ftt ftx fxi fxt fxx i-d i-f idd idf idi idt idx ifd iff ifi ift ifx iid iif iii iit iix itd itf iti itt itx ixi t-x tdd tdf tdi tdt tdx tfd tff tfi tft tfx tid tif tii tit tix ttd ttf tti ttt ttx txf txi txt xdf xdi xdt xft xfx xii xit xix xtf xti xtx xxi xxx