import strutils, sequtils, math

var a = newSeq[int64](100010)

proc f(i, n: int, b: seq[int64]): bool =
  if i > n: return true
  if i mod 2 == 0:
    a[i] = a[i-1] - b[i-1]
    if a[i] <= 0 or 10^18 < a[i]: return false
    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 false
    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
    m: int64 = -1
    que: seq[(int64,int64)] = @[]
    cnt = 0

  que.add((-1.int64, b[0]))

  while que.len > 0 and cnt < 1000:
    var (l, u) = que[0]
    que.delete(0,0)
    m = (l + u) div 2
    a[0] = m
    if f(1, n, b): break
    que.add((l, m))
    que.add((m, u))
    cnt += 1

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

  echo "-1"