-er ddd dde ddf ddi ddp ddr ddx de- ded dee def dei dep der dex dfd dfe dff dfi dfp dfr dfx di- did die dif dii dip dir dix dpd dpe dpf dpi dpp dpr drd dre dri drp drr drx dxd dxi dxp dxr dxx ed- edd ede edf edi edp edr edx eed eee eef eep eer eex ef- efd efe eff efi efp efr efx eid eie eif eii eip eir eix ep- epd epe epf epi epp epr epx erd ere erf eri erp err ex- exd exe exi exp exr exx fdd fde fdf fdi fdp fdr fdx fed fee fef fei fep fer fex ffd ffe fff ffi ffp ffr ffx fid fie fif fii fip fir fix fpd fpe fpi fpp fpr fpx frd fre frf fri frp frr fxe fxi fxp fxr fxx i-d i-f idd ide idf idi idp idr idx ie- ied iee ief iei iep ier iex ifd ife iff ifi ifp ifr ifx iid iie iif iii iip iir iix ipd ipe ipf ipi ipp ipr ipx ir- ird ire irf iri irp irr irx ixe ixi p-p pdd pde pdf pdi pdp pdr pdx ped pee pef pei pep per pex pfd pfe pff pfi pfp pfr pfx pid pie pif pii pip pir pix ppd ppe ppf ppi ppp ppr ppx prd pre prf pri prp prr prx pxe pxr rdd rde rdf rdi rdp rdr rdx re- red ree ref rei rep rer rex rfd rfe rff rfi rfp rfr rid rie rif rii rip rir rix rpd rpe rpf rpi rpp rpr rpx rrd rrf rri rrp rrr rxp rxr xde xdf xdi xdr xed xee xep xer xex xfe xfx xie xii xix xpd xpe xpf xpp xrd xrf xrx xxi xxp xxx