$last_date = <STDIN>;
chomp $last_date;
for (my $i = $last_date; $i <= $bill_date; $i = AddDate( $i, 1)) {
	push @letter_dates, $i;
	printf "Last date %s Bill date %s Data %s\n", $last_date, $bill_date, $i;
}

sub AddDate {
	my $date = $_[0];
	my $x = $_[1]; 			# set this.
	my $day = 24*60*60;
	my $xdays = $x * $day;
	my @t = (localtime(str2time($date) + $xdays))[5,4,3];
	$t[0] += 1900;  # localtime returns years since 1900.
	$t[1] += 1;     # localtime returns month in range 0..11.
	$return_date = sprintf "%04d%02d%02d", $t[0], $t[1], $t[2];
	return $return_date;
}