Given a string s, return the maximum number of ocurrences of any substring under the following rules: The number of unique characters in the substring must be less than or equal to maxLetters. The substring size must be between minSize and maxSize inclusive. Example 1: Input: s = "aababcaab", maxLetters = 2, minSize = 3, maxSize = 4 Output: 2 Explanation: Substring "aab" has 2 ocurrences in the original string. It satisfies the conditions, 2 unique letters and size 3 (between minSize and maxSize). Example 2: Input: s = "aaaa", maxLetters = 1, minSize = 3, maxSize = 3 Output: 2 Explanation: Substring "aaa" occur 2 times in the string. It can overlap. Example 3: Input: s = "aabcabcab", maxLetters = 2, minSize = 2, maxSize = 3 Output: 3 Example 4: Input: s = "abcde", maxLetters = 2, minSize = 3, maxSize = 3 Output: 0 Constraints: 1 <= s.length <= 10^5 1 <= maxLetters <= 26 1 <= minSize <= maxSize <= min(26, s.length) s only contains lowercase English letters.