output_description: Print the answer as an integer.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      A_0 A_1 A_2 \cdots A_N
attempt: N = int(input())
  A = list(map(int, input().split()))
  AA = [0]
  for a in A[1:]:
      AA.append(AA[-1] + a)
  print(AA)
  f = 1 if A[0] == 0 else 0
  r = 1
  b = 1
  for i, a in enumerate(A[1:]):
      x = min(b * 2, AA[-1] - AA[i])
      if i < N - 1 and x > a or i == N - 1 and x == a:
          b = x - a
          r += x
      else:
          f = 0
  print(r if f else -1)
  
problem_description: Statement
  
  Given is an integer sequence of length N+1: A_0, A_1, A_2, \ldots, A_N. Is
  there a binary tree of depth N such that, for each d = 0, 1, \ldots, N, there
  are exactly A_d leaves at depth d? If such a tree exists, print the maximum
  possible number of vertices in such a tree; otherwise, print -1.
samples: [{"input": "3\n    0 1 1 2", "output": "7\n    \n\nBelow is the tree with the maximum possible number of vertices. It has seven\nvertices, so we should print 7.\n\n![0d8d99d13df036f23b0c9fcec52b842b.png](https://img.atcoder.jp/nomura2020/0d8d99d13df036f23b0c9fcec52b842b.png)\n\n* * *"}, {"input": "4\n    0 0 1 0 2", "output": "10\n    \n\n* * *"}, {"input": "2\n    0 3 1", "output": "-1\n    \n\n* * *"}, {"input": "1\n    1 1", "output": "-1\n    \n\n* * *"}, {"input": "10\n    0 0 1 1 2 3 5 8 13 21 34", "output": "264"}]