How to insert a new slide at last position

[shanaki]

For example, I have a presentation file containing slide1, slide2 and slide3.
I want to insert a newslide at last position, slide1, slide2, slide3 and newslide.
When I call Insert(4, newSlide), it throws error due to out of range.

I can insert another position, e.g. slide1, slide2, newslide, slide3 by Insert(3, newslide)
But, I want to insert newslide at last position. Is it ok to just call Add(newslide)?

[shanaki]

It looks like using Add() will work to add slide to the last position. thanks.