sub acmTeam {
    my $topics = shift;
    my $n = @$topics;
    my $m = $n > 0? length($topics->[0]): 0;
    my $max = 0;
    my $max_n = 0;
    for my $i (0 .. $n-2) {
        for my $j ($i + 1 .. $n-1) {
            my $st = 0;
            $st += (substr($topics->[$i], $_, 1) eq '1' || substr($topics->[$j], $_, 1) eq '1'? 1: 0) for (0..$m-1);
            if($st > $max) {
                $max = $st;
                $max_n = 1;
            } elsif($st == $max) {
                ++$max_n;
            }
        }
    }
    return ($max, $max_n);
}