sub get_MD5
  {
   my $md5=Digest::MD5->new;
   my $id;
   my $filename;

  $filename=shift;

  if (open(FF, $filename))
  {
    binmode(FF);
    $md5=Digest::MD5->reset;
    $id = $md5->addfile(*FF)->hexdigest;
    close(FF);
    return $id;
    $md5=Digest::MD5->reset;
  } else
  {
    return "";
  }