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 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.