Furnos. In the alpha case, this group points in the opposite direction as this group. In the beta case, this hydroxyl group points in the same direction as this group here. So for D fructose, an example of a keto HEXOS, the hydroxyl group of the fifth carbon. So carbon number five, this hydroxyl acts as a nucleophile, attacks the carbon of the carbonyl, which happens to be carbon number two, not carbon number one. And so in this case, we form the five member ring.