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. And that's why we call these furnose furnishes. Now, what I haven't actually shown is a second type of reaction can actually take place. So in the case of the defurctose, in the case of all keto hexosis, actually, we can also have under certain circumstances, we can have the hydroxyl group on the 6th carbon attack the carbon of the carbonyl nucleophilically.