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: def sign(X):
      return [-1, 0, 1][(X >= 0) + (X > 0)]
  
  
  N = int(input())
  A = [int(T) for T in input().split()]
  
  AFPCnt = 0
  AFPNow = 0
  for TFP in range(0, N):
      AFPNow += A[TFP]
      if sign(AFPNow) != (-1) ** TFP:
          AFPCnt += abs(AFPNow) + 1
          AFPNow = (-1) ** TFP
  
  AFFCnt = 0
  AFFNow = 0
  for TFF in range(0, N):
      AFFNow += A[TFF]
      if sign(AFFNow) != (-1) ** (TFF + 1):
          AFFCnt += abs(AFFNow) + 1
          AFFNow = (-1) ** (TFF + 1)
  print(min(AFPCnt, AFFCnt))
  
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"}]