const
  n = 10;

var
  f: file of double;

var
  i: integer;
  x: double;
  f_read, f_write: longint;

begin
  assign(f, 'test.ttt');
  rewrite(f);

  for i := 1 to n do
    begin
      write('x(', i, ') = ');
      readln(x); write(f, x)
    end;

  reset(f);

  f_write := 0; f_read := 0;
  while f_read <> filesize(f) do
    begin
      seek(f, f_read);
      read(f, x);
      f_read := filepos(f);

      if x <> 0 then
        begin
          seek(f, f_write);
          write(f, x);
          f_write := filepos(f);
        end;
    end;

  seek(f, f_write); x := 0;
  for i := 1 to filesize(f) - f_write do
    write(f, x);

  { check it: }
  reset(f);
  while not eof(f) do
    begin
      read(f, x);
      writeln(x:8:4)
    end;

  close(f)
end.