use warnings;
use strict;
use DateTime;

my $now = DateTime->now;
my $start = DateTime->new( year=>$now->year-4 );
my $end = $now;

my $dt = $start->clone;
$dt->truncate(to=>'month')->add(months=>1) if $dt->day!=1;
for ( ; $dt<$end; $dt->add(months=>1) ) {
	print $dt->ymd, "\n";
}