10. There are 5 black and white chess pieces arranged in a circle. The rule is: place a white chess piece between two adjacent chess pieces of the same color, and place a black chess piece between two adjacent chess pieces of different colors, then remove the original 5 chess pieces. If starting from the initial state shown in figure (1) and following the above rules, for the situation where there are 5 chess pieces on the circle, the maximum number of black pieces on the circle can be.


10, 4
Solution: Because a black stone is placed between different colored stones, and there are only 5 stones on the circle, there must be two adjacent stones of the same color. Therefore, it is impossible to have 5 black stones. However, after the second operation, there are 4 black stones on the circle. Thus, after each operation, the maximum number of black stones that can appear in the 5 stones on the circle is 4.