If it's 8 am Beijing time, it's 0 am London time.

The place that is 15 hours slower than China is the West Seventh District (-7 time zone), and it was 17 the day before.

It's 20 o'clock in China and 5 o'clock in that place.

That is to say, China X point

If x>= 15, that place is (x- 15) point.

If x