output_description: Print the minimum possible unbalancedness of S'.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      S
attempt: a = input()
  X = a.count("0")
  Y = a.count("1")
  Z = a.count("?") % 2
  q = abs(X - Y) - Z
  print(q)
  
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"}]