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: # coding: utf-8
  import array, bisect, collections, heapq, itertools, math, random, re, string, sys, time
  
  sys.setrecursionlimit(10**7)
  INF = 10**20
  MOD = 10**9 + 7
  
  
  def II():
      return int(input())
  
  
  def ILI():
      return list(map(int, input().split()))
  
  
  def IAI(LINE):
      return [ILI() for __ in range(LINE)]
  
  
  def IDI():
      return {key: value for key, value in ILI()}
  
  
  def solve(n, a):
      ans = 0
      sum = a[0]
      for i in range(1, n):
          now = a[i]
          next_sum = sum + now
          if sum > 0:
              if next_sum > 0:
                  ans += next_sum + 1
                  next_sum = -1
                  sum = next_sum
                  continue
              elif next_sum < 0:
                  sum = next_sum
                  continue
              elif next_sum == 0:
                  next_sum = -1
                  sum = next_sum
                  ans += 1
                  continue
          elif sum < 0:
              if next_sum > 0:
                  sum = next_sum
                  continue
              elif next_sum < 0:
                  ans += abs(next_sum) + 1
                  next_sum = 1
                  sum = next_sum
                  continue
              elif next_sum == 0:
                  next_sum = 1
                  sum = next_sum
                  ans += 1
                  continue
          elif sum == 0:
              sum = next_sum
              continue
  
      return ans
  
  
  def main():
      n = II()
      a = ILI()
      print(solve(n, a))
  
  
  if __name__ == "__main__":
      main()
  
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"}]