my @c = split /,/, $hand;
    my $total = 0;

    # 2 cards
    for my $i1 (0..4) {
       for my $i2 ($i1+1..4) {
          $total += 2 if $c[$i1] + $c[$i2] == 15;
       }
    }

    # 3 cards
    for my $i1 (0..4) {
       for my $i2 ($i1+1..4) {
          for my $i3 ($i2+1..4) {
             $total += 2 if $c[$i1] + $c[$i2] + $c[$i3] == 15;
          }
       }
    }

    ...