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())
  N=list(map(int,input().split()))
  emptylists=[]
  number=0
  for i in range(n):
  	number+=N[i]
      emptylists.append(number)
  ans1=0
  use=0
  for i in range(n):
      #偶数番が正、奇数番が負の時
      if i%2==0:
          #奇数番め
          if emptylists[i]+use<0:
              continue
          if emptylists[i]+use>=0:
              ans1+=emptylists[i]+1  
              use=use-emptylists[i]-1
          
      if i%2!=0:
          #偶数番め
          if emptylists[i]+use>0:
              continue
          if emptylists[i]+use<=0:
              ans1+=1-emptylists[i]-use
              use=use+1-emptylists[i]
  ans2=0
  uses=0
  for i in range(n):
      #偶数番が負、奇数番が正の時
      if i%2!=0:
          #ぐう数番め
          if emptylists[i]<0:
              continue
          if emptylists[i]>=0:
              ans2+=emptylists[i]+1  
              uses=uses-emptylists[i]-1       
      if i%2==0:
          #き数番め
          if emptylists[i]>0:
              continue
          if emptylists[i]<=0:
              ans2+=1-emptylists[i]-uses
              uses=uses+1-emptylists[i]
  print(min(ans1,ans2)) 
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"}]