When people drink some tea in the teahouse, they also play some casual games. Now, inverting cups is a popular game. The meaning of the question is, now there are some cups which are upturned, we can regard the total number of the cups as a positive integer number A , and we can invert some cups, the number is B and B is also a positive integer number. We define one retroflexion that if the original cup is upturned, one retroflexion makes it downward, and if the original cup is downward, one retroflexion makes it upturned. So the question is if the whole original cups are upturned , can we invert these cups to make all the cups downward? And if it is possible, how many is the least of times?