output_description: Print the maximum possible final value of x in a sequence of operations such
  that S equals T in the end.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      T
attempt: input()
  print(1)
  
problem_description: Statement
  
  Takahashi has an empty string S and a variable x whose initial value is 0.
  
  Also, we have a string T consisting of `0` and `1`.
  
  Now, Takahashi will do the operation with the following two steps |T| times.
  
    * Insert a `0` or a `1` at any position of S of his choice.
    * Then, increment x by the sum of the digits in the odd positions (first, third, fifth, ...) of S. For example, if S is `01101`, the digits in the odd positions are `0`, `1`, `1` from left to right, so x is incremented by 2.
  
  Print the maximum possible final value of x in a sequence of operations such
  that S equals T in the end.
samples: [{"input": "1101", "output": "5\n    \n\nBelow is one sequence of operations that maximizes the final value of x to 5.\n\n  * Insert a `1` at the beginning of S. S becomes `1`, and x is incremented by 1.\n  * Insert a `0` to the immediate right of the first character of S. S becomes `10`, and x is incremented by 1.\n  * Insert a `1` to the immediate right of the second character of S. S becomes `101`, and x is incremented by 2.\n  * Insert a `1` at the beginning of S. S becomes `1101`, and x is incremented by 1.\n\n* * *"}, {"input": "0111101101", "output": "26"}]