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

You are given a string s consisting of the characters 'a', 'b', and 'c' and a non-negative integer k. Each minute, you may take either the leftmost character of s, or the rightmost character of s.
Return the minimum number of minutes needed for you to take at least k of each character, or return -1 if it is not possible to take k of each character.
 
Please complete the following python code precisely:
```python
class Solution:
    def takeCharacters(self, s: str, k: int) -> int:
```