I would like help understanding this slide from my class, especially the inner loop part. I do not understand how he is getting at n - (n - 1 - 1) = 2
I do understand that when j = n - 1 we get n - (n - 1) but I don't get why we have an extra -1 there.
I'd appreciate if anyone could walk through their thought process for this, thank you!

2.…for i = (j+1)….Suggest using a font where the glyphs for $I, l$ and $1$ can be told from each other. $\endgroup$