class Solution:
  def maxUniqueSplit(self, s: str) -> int:
    
    def backtrack(s, seen, index):
      if index == len(s):
        return len(seen)

      max_split = 0        
    
      # from: index + 1 as we want to start from the index to --> any possible next character 
      # to: len(s) + 1 because s[start: end] the syntax in not inclusive to the end  
      for i in range(index + 1, len(s) + 1):
        substring = s[index: i]
        if substring not in seen:
          seen.add(substring)
          max_split = max(max_split, backtrack(s, seen, i))
          seen.remove(substring)
      
      return max_split
    
    return backtrack(s, set(), 0)