sub divisibleSumPairs {
    my ($n, $k, $s) = @_;

    my $res = 0;
    for (my $i = 0; $i < $n; $i++) {
        for (my $j = 0; $j < $n; $j++) {
            $res++ if ($i < $j && (($s->[$i] + $s->[$j]) % $k) == 0 );
        }
    }
    return $res;
}