use strict;

use DateTime::Duration;
use DateTime;

# These are local standard times in Europe/Rome, i.e. always UTC+0100
my @dates = (
   [2020,12,2,1,0],
   [2021,7,2,1,0]
);

my $timezone = '+0100';

# This is the duration to be added to go from LST to UTC
my $seconds = -($timezone/100) * 3600;

my $dur = DateTime::Duration->new(
    years       => 0,
    months      => 0,
    weeks       => 0,
    days        => 0,
    hours       => 0,
    minutes     => 0,
    seconds     => $seconds,
    nanoseconds => 0
);

for my $date (@dates) {

    my $dt = DateTime->new(
        year =>    => $date->[0],
        month      => $date->[1],
        day        => $date->[2],
        hour       => $date->[3],
        minute     => $date->[4],
        second     => 0,
        nanosecond => 0,
        time_zone  => 'UTC'
    );

    $dt->add($dur); # This is a DateTime object in LST

    print "LST: ",join("-",@{$date}),"\n";
    print "UTC: ",$dt->set_time_zone("UTC"),"\n";
    print "LT:  ",$dt->set_time_zone("Europe/Rome"),"\n";

}