Chicago to Shanghai....less than 72 hours then to Vietnam....Cambodia....Back to Shanghai..

Hi -

I am flying from Chicago into Shanghai - arriving December 9th at 3.05 PM. Flying out of Shanghai to Saigon, Vietnam on December 11th at 9:55 PM, so less than 72 hours in Shanghai.

During this trip I go from Vietnam to Cambodia, then fly back to Shanghai on December 22nd and home to Chicago...

Will I qualify for the 72 hour Visa I can obtain at the airport in Shanghai when I land on December 9th??