Man, there's a (pc) software called Kingo Android Root. You only need to enable USB debugging and connect to PC, and press one button. 30 seconds and it is rooted. Works for almost every device. Tried on I9300 4.3 and it works.
Try flashing this ;)
Thank you very much :good:
All softly edit...
I came from S3. Totally new life with G3. No regrets.