Pick a random image of an album of imgur

I need a php function to pick a random image of a predetermined album of imgur.

For example, I have this album: http://ift.tt/1KMZg66

I want to get a randomd url of the image, for example: http://ift.tt/1KYi71A

This is for a Wordpress blog I have been working on, and my knowledge of PHP is low.