input: from typing import List
  from math import comb
  
  def number_of_substrings(s: str, ch: str) -> int:
      """
      Given a string s and a character ch, find the total count of substrings 
      in s that have ch as their starting and ending character.
  
      Examples:
      >>> s = "abada", ch = "a"
      6
      >>> s = "zzz", ch = "z"
      6
  
      Constraints:
      1 <= len(s) <= 10^5
      Both s and ch consist only of lowercase English letters.
      """
output:     
      count = 0
      n = len(s)
      for i in range(n):
          if s[i] == ch:
              for j in range(i, n):
                  if s[j] == ch:
                      count += 1
      return count
  