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 ARC072C():
      N = int(input())
      a = list(map(int, input().split()))
      cnt1 = 0
      cnt2 = 0
      sum1 = a[0]
      sum2 = a[0]
      if sum1 <= 0:
          cnt1 = 1 - a[0]
          sum1 = 1
      if sum2 >= 0:
          cnt2 = abs(-1 - a[0])
          sum2 = -1
      j = 1
      # print(sum1, sum2)
      for i in range(1, N):
          sum1 += a[i]
          sum2 += a[i]
          if j % 2 == 0:
              if sum1 <= 0:
                  cnt1 += 1 - sum1
                  sum1 = 1
              if sum2 >= 0:
                  cnt2 += abs(-1 - sum2)
                  sum2 = -1
          else:
              if sum1 >= 0:
                  cnt1 += abs(-1 - sum1)
                  sum1 = -1
              if sum2 <= 0:
                  cnt2 += 1 - sum2
                  sum2 = 1
          j += 1
          # print(sum1, sum2)
      # print(cnt1, cnt2)
      print(min(cnt1, cnt2))
  
  
  ARC072C()
  
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"}]