Problem with animation (transition of images)

hello! bros I’m new to all this… I found a very interesting animation in codepen that I want to add to my web page. However, I can’t add more than 2 images, which are the ones that come by default… can someone help me?

This is the link of the animation:

What changes should I make in the code so that the animation has 4 images?

please help!! :frowning: