import sequtils
proc getchar_unlocked():char {. importc:"getchar_unlocked",header: "<stdio.h>" .}
proc scan(): int =
  var minus = false
  block:
    let k = getchar_unlocked()
    if k == '-' : minus = true
    else: result = 10 * result + k.ord - '0'.ord
  while true:
    let k = getchar_unlocked()
    if k < '0' or k > '9': break
    result = 10 * result + k.ord - '0'.ord
  if minus: result *= -1

let n = scan()
var A = newSeqWith(n+1,scan())
for i in countdown(n, 3): A[i-2] += A[i]
if n >= 3 and A[2] != 0:
  echo 2,"\n",A[0]," ",A[1]," ",A[2]
elif n >= 2 and A[1] != 0:
  echo 1,"\n",A[0]," ",A[1]
else:
  echo 0,"\n",A[0]