uses
   crt,
   dos;

var
  key:string;

{ decode file ---------------------------------------------------------------}
{your code here}
procedure decode(infname:pathstr);
var
  infile,outfile:file;
  fdir:dirstr; fname:namestr; fext:extstr;
  dbuf,sbuf:pointer;
  idx,i,j,srcseg,srcofs,dstseg,dstofs,start,csize:word;
  src,rep:byte;
begin
  if maxavail<2*65500 then Begin
Writeln(#13#10,''No Memory'');
halt;
End;
getmem(dbuf,65500);
getmem(sbuf,65500);
srcseg:=seg(sbuf^); srcofs:=ofs(sbuf^);
dstseg:=seg(dbuf^); dstofs:=ofs(dbuf^); start:=dstofs;
assign(infile,infname);
{$i-} reset(infile,1); {$i+}
if ioresult<>0 then Begin
     Writeln(#13#10''File I/O!'');
     halt;
  End;
  if filesize(infile)>65500 then halt;
  blockread(infile,sbuf^,filesize(infile));
  csize:=filesize(infile);
  close(infile);
  randseed:=ord(key[length(key)]); j:=0;
  for i:=0 to csize do begin
    mem[srcseg:srcofs+i]:=mem[srcseg:srcofs+i] xor
(ord(key[j])+random(ord(key[j])));
    j:=1+j mod 8;
  end;
  idx:=0;
  while idx
0 then Begin
     Writeln(#13#10''Output Error!'');
     halt(4);
  End;
  blockwrite(outfile,key,length(key)); {so I know which key did it!}
  blockwrite(outfile,dbuf^,csize);        {un encoded}
  close(outfile);
  freemem(sbuf,65500);
  freemem(dbuf,65500);
end;

{ main ----------------------------------------------------------------------}

Procedure ShowFile(FName:String); {just a test not used in live version!}
Var
   T:Text;
   S:String;

Begin
   Assign(T,FName);
   ReSet(T);
   While not eof(t) do begin
{$I-}      Readln(t,s); {$I+}
      Writeln(s);
   End;
   Close(T);
End;

Var
   Cnt1:Integer;        {character 1}
   Cnt2:Integer;        {2}
   Cnt3:Integer;        {3}
   Cnt4:Integer;        {4}
   Cnt5:Integer;        {5}
   Cnt6:Integer;        {6}
   Cnt7:Integer;        {7}
   Cnt8:Integer;        {8}
   Ch:Char;        &nbs