let n = Int(readLine()!)!


func solve(_ a: [Int]) -> [Int] {
  let n = a.count
  var ans: [Int] = .init(repeating: 0, count: n + 1)
  for i in (1...n).reversed() {
    var sum = 0
    var j = i + i
    while j <= n {
      sum ^= ans[j]
      j += i
    }
    ans[i] = sum ^ a[i]
  }
  return ans
}

var a: [Int] = .init(repeating: 0, count: n + 1)
let inputs = readLine()!
	.split(separator: " ")
	.map { Int($0)! }
	.enumerated()
	.forEach { a[$0+1] = $1 }

let ans = solve(a)

if ans.isEmpty {
  print(-1)
} else {
  let res = ans.enumerated().filter { $1 == 1 }
  print(res.count)
  res.forEach { print($0.0 + 1) }
}