Arrange icons in a grid in Photoshop/Illustrator

I have a collection of icons (>100) I'd like to place into Illustrator or Photoshop (have both, either is fine) and arrange them in a grid like this.

What's the quickest way to 1) Load the icons into Illustrator/Photoshop (preferably not one-by-one by hand?) and 2) Arrange them into a grid?

Cheers.