There are 18 piles of stones, each pile of stones is 100 stones, 17 piles are randomly selected, and one stone is taken from each pile and placed in the remaining pile of stones. This is called an operation, and every operation in the future will be like this The operation is carried out in the same way. After less than 40 such operations, it is found that there are 70 stones in one pile, and the number of stones in another pile is between 190 and 200. What is the exact number of stones in this pile? Briefly explain why.
有18堆石子，每堆石子都是100个石子，随意挑选17堆，从每堆中各取一个石子放到剩下那堆石子里，这称为一次操作，以后每次操作都如这次操作一样进行，经过不到40次这样操作后，发现有一堆的石子70个，另有一堆的石子数在190至200之间，问这堆石子的准确数是多少？简要说明理由．
<result>196</result>