use strict;
use warnings;
use List::Util qw(uniq);

my @nums = (17, 10, 20, 33, 30, 40, 10, 33, 40, 15, 16, 17);

my @un_nums = uniq(@nums);

local $" = ":";
print "@un_nums\n";

##</code><code>##

17:10:20:33:30:40:15:16