Array filler

program ArrayFiller;
uses SysUtils;
var a:array of array of Integer;
  foutname:String;
  Fout:Text;
  hbd:Boolean; //has been destroyed
  i,j,m,n:Word;
  IORes:Integer;
  fillfunc:function(x:Integer):Integer;
  range:Integer;
  neg:Char;

function NegFiller(range:Integer):Integer;
var res:Integer;
begin
  res:=random(range*2)-range;
  NegFiller:=res;
end;
function PosFiller(range:Integer):Integer;
var res:Integer;
begin
  res:=random(range);
  PosFiller:=res;
end;
//main
begin
  WriteLn('I see you are in deep trouble');
  WriteLn('Tough times have come');
  WriteLn('Which file should I fill?');
  foutname:='';
  ReadLn(foutname);
  while foutname='' do
  begin
    WriteLn('Write some filename, fool!');
    ReadLn(foutname);
  end;
  Assign(Fout,foutname);
  hbd:=False;
  if FileExists(foutname) then hbd:=True;
  {$I-}
  ReWrite(Fout);
  {$I+}
  IORes:=IOResult;
  if IORes<>0 then
  begin
    WriteLn('Even I cannot solve your problem this way.');
    WriteLn('Input/Output error #',IORes);
    ReadLn();
    halt(IORes);
  end;
  if hbd then WriteLn('That file has just been sacrificed.');
  WriteLn;
  Write('How big your trouble is? (rows, columns): ');
  ReadLn(m,n);
  WriteLn(Fout,m,' ',n);
  SetLength(a,m+1,n+1);
  WriteLn('Now I shall call the Great Randomizer.');
  Randomize;
  Write('Would you want to limit it? (int.) :');
  ReadLn(range);
  Write('Negatives? (y/n)');
  ReadLn(neg);
  case neg of
    'y': fillfunc:=@NegFiller;
    'n': fillfunc:=@PosFiller;
  end;
  for i:=1 to m do
  begin
    for j:=1 to n do
    begin
      a[i,j]:=fillfunc(range);
      Write(Fout,a[i,j]:3,' ');
    end;
  WriteLn(Fout);
  end;

  Close(Fout);
  WriteLn('Your praises have been answered.');
  WriteLn('Check the ',foutname);
  ReadLn();
end.