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(i) for i in input().split()]
  s0 = a[0]
  count=0
  
  i=0
  while a[i]!=0and i!=n-1:i++
  if a[i]>0:
    s0+=1
    count+=1
  else:
    s0-=1
    count+=1
    
  
    for i in range(1,n):
    s1 = s0+a[i]
    if s0*s1>=0:
      if s1>0:
        a[i]-=(abs(s1)+1)
        count+=(abs(s1)+1)
      elif s1<0:
        a[i]+=(abs(s1)+1)
        count+=(abs(s1)+1)
      elif s1==0:
        if s0>0:
          a[i]-=1
          count+=1
        elif s0<0:
          a[i]+=1
          count+=1
    s0 += a[i]
  print(count)
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"}]