8. (10 points) An integer has 2016 digits. Add the digits of this integer, then add the digits of the resulting integer. What is the maximum possible value of the final sum? $\qquad$

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【Analysis】When each digit of this 2016-digit integer is 9, the sum of its digits is maximized, which is $9 \times 2016$ $=18144$, so the sum of the digits of any 2016-digit number does not exceed 18144. Next, analyze the sum of the digits of a number that is no greater than 18144.

【Solution】Solution: The maximum sum of the digits of a 2016-digit number occurs when all 2016 digits are 9, with the maximum sum being: $9 \times 2016=18144$. The problem then becomes analyzing the maximum sum of the digits of a number that is less than or equal to 18144,

First, consider 17999,9999,
It is known that: the maximum sum of the digits of 9999 is 36.
Therefore, the answer to this problem is: 36.