output_description: Print the minimum possible unbalancedness of S'.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      S
attempt: S = list(input())
  
  
  def long_repeat(line):
  
      max = 0
      cnt = 1
  
      for i in range(len(line) - 1):
          if cnt > 1:
              cnt -= 1
              continue
          for j in range(i + 1, len(line)):
              if line[i] == line[j]:
                  cnt += 1
              else:
                  break
          if max < cnt:
              max = cnt
  
      return max
  
  
  s = long_repeat(S)
  
  if len(S) <= s + 1:
      print(s - 1)
  else:
      print(s)
  
problem_description: Statement
  
  Given is a string S, where each character is `0`, `1`, or `?`.
  
  Consider making a string S' by replacing each occurrence of `?` with `0` or
  `1` (we can choose the character for each `?` independently). Let us define
  the unbalancedness of S' as follows:
  
    * (The unbalancedness of S') = \max \\{ The absolute difference between the number of occurrences of `0` and `1` between the l-th and r-th character of S (inclusive) :\ 1 \leq l \leq r \leq |S|\\}
  
  Find the minimum possible unbalancedness of S'.
samples: [{"input": "0??", "output": "1\n    \n\nWe can make S'= `010` and achieve the minimum possible unbalancedness of 1.\n\n* * *"}, {"input": "0??0", "output": "2\n    \n\n* * *"}, {"input": "??00????0??0????0?0??00??1???11?1?1???1?11?111???1", "output": "4"}]