randomize frames

Hello, Please take a look at the attached .fla file. When you start the presentation, you will see some actionscript that simply makes navigation possible to go back and forth through the first 3 frames. I would like to add this randomization feature: Once users click on the next button in slide 3, they will be taken to any random frame between frame 4 and 13. Once the user has gone through all the frames, they will be taken to slide 14. Please note that I don't want users to be taken to a frame more than once. I hope this will be possible and easy to do. Thanks in advance