How many kind of independent data points do we actually have? Well, for each of these, so over here, if you know, we have n data points in each one. In particular, n is 3 here. But if you know n minus 1 of them, you can always figure out the nth one if you know the actual sample mean. So in this case, for any of these groups, if you know 2 of these data points, you can always figure out the third. If you know these 2, you can always figure out the third if you know the sample mean. So in general, let's figure out the degrees of freedom here.