#! perl
use strict;
use warnings;
use Math::Combinatorics;
 
my  @n   = qw(a e i o u);
my  $com = Math::Combinatorics->new
    (
        count => 2,
        data  => [@n],
    );

my  $s = join(' ', @n);    

print '-' x (24 + length $s), "\n";
print "Combinations of 2 from: $s\n";
print '-' x (24 + length $s), "\n";

while (my @combo = $com->next_combination)
{
    print join(' ', @combo), "\n";
}