You are given a string s consisting of lowercase English letters.

Return an integer denoting the maximum number of substrings you can split s into such that each substring starts with a distinct character (i.e., no two substrings start with the same character).

Example 1:

Input: s = "abab"

Output: 2

Explanation:

Split "abab" into "a" and "bab".
Each substring starts with a distinct character i.e 'a' and 'b'. Thus, the answer is 2.

Example 2:

Input: s = "abcd"

Output: 4

Explanation:

Split "abcd" into "a", "b", "c", and "d".
Each substring starts with a distinct character. Thus, the answer is 4.

Example 3:

Input: s = "aaaa"

Output: 1

Explanation:

All characters in "aaaa" are 'a'.
Only one substring can start with 'a'. Thus, the answer is 1.

Constraints:

1 <= s.length <= 10⁵
s consists of lowercase English letters.