#!/usr/bin/perl -w
use strict;
use DateTime;

my $secs;

for my $year (1960..2005) {
  for my $date ([30,6], [31,12]) {
    my $now = DateTime->new(
          year   => $year,
          month  => $date->[1],
          day    => $date->[0],
          hour   => 23,
          minute => 59,
          second =>  0,
          time_zone => "UTC");

    my $later = $now->clone()->add(
            seconds => 60);

    $later->set_time_zone("Europe/London");

    if($later->second() == 60) {
        print $later->dmy(), " ",
              $later->hms(), ": ",
              ++$secs, "\n";
    }
  }
}