use strict;

my $rRecord;
my @List;
my @SortedList;
$rRecord = [12]; push(@List, $rRecord);
$rRecord = [3]; push(@List, $rRecord);
$rRecord = [9]; push(@List, $rRecord);
$rRecord = [1]; push(@List, $rRecord);
@SortedList = sort { $List[$a][0] <=> $List[$b][0] } @List;
my $Print = '';
for( my $i = 0; $i <= $#SortedList; $i++ ) {
    $Print .= " $SortedList[$i][0]";
}
print "$Print\n";