use 5.010;
use Time::Piece;
use Time::Seconds qw( ONE_DAY ONE_HOUR );

sub last_day_of_last_month ()
{
	my $now = localtime;
	my $day = Time::Piece->new(
		$now - ($now->day_of_month * ONE_DAY)
	);
	$day += ONE_HOUR * ($now->isdst <=> $day->isdst);
	return $day;
}

say last_day_of_last_month->mdy('/');