You are given a string `s` containing lowercase letters and an integer `k`. You need to :

- First, change some characters of `s` to other lowercase English letters.
- Then divide `s` into `k` non-empty disjoint substrings such that each substring is a palindrome.

Return the minimal number of characters that you need to change to divide the string.

Example 1:

    Input: s = "abc", k = 2
    Output: 1
    Explanation: You can split the string into "ab" and "c", and change 1 character in "ab" to make it palindrome.

Example 2:

    Input: s = "aabbc", k = 3
    Output: 0
    Explanation: You can split the string into "aa", "bb" and "c", all of them are palindrome.

Example 3:

    Input: s = "leetcode", k = 8
    Output: 0

Constraints:

- `1 <= k <= s.length <= 100`.
- `s` only contains lowercase English letters.