1. 202 There are three piles of stones. Each time, A moves one stone from one pile to another, and A can receive payment from B after each move, the amount of which equals the difference between the number of stones in the pile where the stone is placed and the number of stones in the pile where the stone is taken from. If this difference is negative, A must return this amount of money to B (if A has no money to return, it can be temporarily owed). At a certain moment, all the stones are back in their original piles. Try to find the maximum possible amount of money A could have earned up to this moment.
[Solution] The amount of money A earns is 0.
In fact, we can imagine that initially, in each pile of stones, there is exactly one line segment connecting any two stones. When A moves a stone, he first unties the line segments connecting this stone to other stones, and then uses these line segments to connect this stone to the other stones in the new pile. If the original line segments are not enough, he asks B for more; if the original line segments are too many, he returns them to B.

Obviously, when the original line segments are not enough, this indicates that the number of stones remaining in the original pile is less than the number of stones in the pile where he will place the stone. At this time, the number of line segments he asks B for is equal to the amount of money he owes B (or temporarily owes B); when the original line segments are too many, this indicates that the number of stones remaining in the original pile is more than the number of stones in the pile where he will place the stone. At this time, the number of line segments he returns to B is equal to the amount of money he earns from B.

When all the stones are in their original piles, the number of line segments connecting the stones has neither increased nor decreased. Therefore, at this time, A neither owes B money nor has received any payment from B, so the total amount of money A earns is 0.