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()))
  
  ans = 0
  s = A[0]
  if s > 0:
    flag = 1
  elif s < 0:
    flag = -1
  elif if A[1] < 0:
    flag = 1
    ans += 1
  else:
    flag = -1
    ans += 1
  for i in range(1,N):
    s += A[i]
    if flag == 1 and s >= 0:
      ans += s + 1
      s = -1
    elif flag == -1 and s <= 0:
      ans += 1 - s
      s = 1
    flag *= -1
  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"}]