72 hour travel visa eligibility. VANCOUVER, SHANGHAI, JEJU, SHANGHAI

Hi I'm wondering if I'll be eligible for the 72 hour free transit. When I reach my final destination in shanghai at the end I will have a student X. But the student X is one entry not multiple and I already had this trip planned from shanghai to jeju so I will be in Shanghai first for 24 hours fly to jeju then come back to shanghai with my student X. Wondering if I am eligible

Thanks