output_description: Print the minimum necessary count of operations.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      n
      a_1 a_2 ... a_n
attempt: input()
  (*A,) = map(int, input().split())
  f = True
  s1 = 0
  r1 = 0
  s2 = 0
  r2 = 0
  for a in A:
      s1 += a
      s2 += a
      if f and s1 <= 0:
          r1 += 1 - s1
          s1 = 1
      elif not (f) and s1 >= 0:
          r1 += s1 + 1
          s1 = -1
      if not (f) and s2 <= 0:
          r2 += 1 - s2
          s2 = 1
      elif f and s2 >= 0:
          r2 += s2 + 1
          s2 = -1
      f = not (f)
  print(min(r1, r2))
  
problem_description: Statement
  
  You are given an integer sequence of length N. The i-th term in the sequence
  is a_i. In one operation, you can select a term and either increment or
  decrement it by one.
  
  At least how many operations are necessary to satisfy the following
  conditions?
  
    * For every i (1≤i≤n), the sum of the terms from the 1-st through i-th term is not zero.
    * For every i (1≤i≤n-1), the sign of the sum of the terms from the 1-st through i-th term, is different from the sign of the sum of the terms from the 1-st through (i+1)-th term.
samples: [{"input": "4\n    1 -3 1 0", "output": "4\n    \n\nFor example, the given sequence can be transformed into 1, -2, 2, -2 by four\noperations. The sums of the first one, two, three and four terms are 1, -1, 1\nand -1, respectively, which satisfy the conditions.\n\n* * *"}, {"input": "5\n    3 -6 4 -5 7", "output": "0\n    \n\nThe given sequence already satisfies the conditions.\n\n* * *"}, {"input": "6\n    -1 4 3 2 -5 4", "output": "8"}]