import strutils, sequtils, math

var a = newSeq[int64](100010)

proc f(i, n: int, b: seq[int64]): int64 =
  if i > n: return -1
  if i mod 2 == 0:
    a[i] = a[i-1] - b[i-1]
    if a[i] <= 0 or 10^18 < a[i]: return abs(a[i])
    return f(i+1, n, b)
  else:
    a[i] = b[i-1] - a[i-1]
    if a[i] <= 0 or 10^18 < a[i]: return abs(a[i])
    return f(i+1, n, b)

when isMainModule:
  var
    n = stdin.readLine.parseInt
    b = newSeq[int64](n)

  for i in 0..n-1:
    b[i] = stdin.readLine.parseBiggestInt

  if n == 1:
    if b[0] <= 1: echo "-1"
    else:
      echo 2
      echo 1
      echo b[0] - 1
    quit()

  # var p = 1
  # while p < b[0]:
  #   a[0] = p
  #   echo f(1, n, b)
  #   p += 1

  var
    l: int64 = -1
    r: int64 = b[0]
    cnt: int = 0
    pos: int64 = -1

  while r - l > 10:
    var
      x = (l + l + r) div 3
      y = (l + r + r) div 3
    a[0] = x
    let xf = f(1, n, b)
    a[0] = y
    let yf = f(1, n, b)
    if xf > yf:
      l = x
    else:
      r = y
    cnt += 1


  for i in max(1, l-100)..min(b[0]-1, l+100):
    a[0] = i
    if f(1, n, b) == -1:
      echo n+1
      for i in 0..n:
        echo a[i]
      quit()

  for i in max(1, r-100)..min(b[0]-1, r+100):
    a[0] = i
    if f(1, n, b) == -1:
      echo n+1
      for i in 0..n:
        echo a[i]
      quit()


  echo "-1"