HI 144 hour visa free transit

We arrive in Beijing on the 29th of Nov at 4:45pm and depart at 6:30pm on Dec 5th from USA. We qualify for the 144 hour free time wise. But my question is, can we tour both Beijing and Shanghai during our stay, or are we require to stay within the confines of Beijing? We planned on landing in Beijing, staying a couple days, taking the train to Shanghai, staying a couple days there, train back then fly out back to USA.