Buying a round trip ticket to shang hai but leaving and coming back

i'd like to go to shang hai for 3 nights then phuket for 6 back to shang hai for 1 night before returning home to canada. I would buy 2 round tickets. canada to shang hai (march 24 & april 5) and shang hai to phuket (march 28 & april 4). can i do this on the 144 visa-free travel?