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 = [int(x) for x in input().split()]
  for num, i in enumerate(a):
      if i != 0:
          non0 = num
          break
  if non0 == 0:
      ans = 0
  elif non0 == 1:
      ans = 2
  else:
      ans = (non0 - 2) * 2 + 2
  Sum = a[non0]
  if a[non0] > 0:
      flag = +1
  else:
      flag = -1
  for i in range(non0 + 1, n):
      Sum += a[i]
      if flag == 1:
          if Sum >= 0:
              ans += Sum + 1
              Sum = -1
          flag = -1
      elif flag == -1:
          if Sum <= 0:
              ans += 1 - Sum
              Sum = 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"}]