Can I fly into Shanghai, take train to Beijing and back, and still fly out of Shangh on 144 hr twov?

Vancouver - Tokyo- Shanghai (then take train for a couple day stay in Beijing and then train back to Shanghai)i - Tokyo (few hour layover - Vancouver. I guess I just needed clarification the 144 hour free transit works as long as you FLY in and out of the same region (yet can travel by train and back) to another region during your stay?