sub nijo {
  use bytes;
  my ($s1, $s2) = @_;
  my $idx = 0;
  my $len;

  my @chunks = split /\0/, $s1;

  foreach my $chunk (@chunks) {
    $len = length($chunk);
    substr ($s2, $idx, $len) = $chunk;
    $idx = $idx + 1 + $len;
  }
  return $s2;
}