The algorithm for arriving in Xi 'an on the third day is: arriving on the same day is one day. For example, it is the first day to arrive in Xi 'an on May 29th, and the third day refers to May 3rd1,that is, two days later.
Xi 'an strengthened epidemic prevention and control: temperature measurement, inspection of Shaanxi health code and big data travel code, information registration, on-site nucleic acid sampling before release, inspection of nucleic acid certificates within 48 hours of returning personnel from epidemic provinces, and another nucleic acid test on the third day after arrival in Xi 'an.