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: N = int(input())
  A = list(map(int, input().split()))
  cur = A[0]
  ans = 0
  isplus = True
  ind = 1
  if cur < 0:
      isplus = False
  if cur == 0:
      # すべて0の場合
      allzero = True
      firstNotZero = 0
      firstNotZeroInd = 0
      for i in range(N):
          if A[i] != 0:
              firstNotZero = A[i]
              firstNotZeroInd = i
              allzero = False
              break
      if allzero:
          print(N)
          exit(0)
      # 0以外が出てくる場合
      if firstNotZero > 0:
          cur = -1
          ind = firstNotZeroInd
          isplus = False
      else:
          cur = 1
          ind = firstNotZeroInd
          isplus = True
  
  for i in range(ind, N):
      if isplus:
          if cur + A[i] >= 0:
              diff = abs((cur + A[i]) - (-1))
              ans += diff
              cur = -1
          else:
              cur += A[i]
          isplus = False
      else:
          if cur + A[i] <= 0:
              diff = abs((cur + A[i]) - 1)
              ans += diff
              cur = 1
          else:
              cur += A[i]
          isplus = True
  
  print(ans)
  
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"}]