Please solve the programming task below using a self-contained code snippet in a markdown code block.

You are given a 0-indexed integer array nums and an integer k. You have a starting score of 0.
In one operation:

choose an index i such that 0 <= i < nums.length,
increase your score by nums[i], and
replace nums[i] with ceil(nums[i] / 3).

Return the maximum possible score you can attain after applying exactly k operations.
The ceiling function ceil(val) is the least integer greater than or equal to val.
 
Please complete the following python code precisely:
```python
class Solution:
    def maxKelements(self, nums: List[int], k: int) -> int:
```