That's the total degrees of freedom we had for all of the data combined. It even works if you look at the more general. So our sum of squares between had m minus 1 degrees of freedom. Our sum of squares within had m times n minus 1 degrees of freedom. So this is equal to m minus 1 plus mn minus m. These guys cancel out. This is equal to mn minus 1 degrees of freedom, which is exactly the total degrees of freedom we had for the total sum of squares. So the whole point of the calculations that we did in the last video and in this video is just to appreciate that this total variation over here, this total variation that we first calculated, can be viewed as the sum of these kind of two component variations.