Count Case-Insensitive Symmetric Triplets in a String

Problem: Count Case-Insensitive Symmetric Triplets in a String Given a string s, count the number of contiguous substrings of length 3 s[i..i+2] (0 <= i <= len(s)-3) such that: s[i] and s[i+2] are the same case-insensitively. Return the total count. Input One line string s. Output An integer: the number of valid contiguous triplets. Constraints 1 <= |s| <= 2 * 10^5 Examples s = "axA" → output 1 s = "cXcBdB" → output 2 Example Input axA Output 1