my $prev;
my $sum;
my $max = -1;
for (@array) {
   if (defined($prev) && $_ == $prev+1) {
      $prev = $_;
      $sum += $_;
      next;
   }

   if (defined($prev)) {
      $max = $sum if $sum > $max;
      undef $prev;
      undef $sum;
   }

  #if ($_ >  0) {  # zero isn't considered positive
   if ($_ >= 0) {  # zero is    considered positive
      $prev = $_;
      $sum  = $_;
   }
}