Problem:
Score : 400 points

Problem Statement

There are N empty boxes arranged in a row from left to right.
The integer i is written on the i-th box from the left (1 \leq i \leq N).

For each of these boxes, Snuke can choose either to put a ball in it or to put nothing in it.

We say a set of choices to put a ball or not in the boxes is good when the following condition is satisfied:

For every integer i between 1 and N (inclusive), the total number of balls contained in the boxes with multiples of i written on them is congruent to a_i modulo 2.

Does there exist a good set of choices? If the answer is yes, find one good set of choices.

Constraints

All values in input are integers.

1 \leq N \leq 2 \times 10^5

a_i is 0 or 1.

Input

Input is given from Standard Input in the following format:

N
a_1 a_2 ... a_N

Output

If a good set of choices does not exist, print -1.

If a good set of choices exists, print one such set of choices in the following format:

M
b_1 b_2 ... b_M

where M denotes the number of boxes that will contain a ball, and b_1,\ b_2,\ ...,\ b_M are the integers written on these boxes, in any order.

Sample Input 1

3
1 0 0

Sample Output 1

1
1

Consider putting a ball only in the box with 1 written on it.

There are three boxes with multiples of 1 written on them: the boxes with 1, 2, and 3. The total number of balls contained in these boxes is 1.

There is only one box with a multiple of 2 written on it: the box with 2. The total number of balls contained in these boxes is 0.

There is only one box with a multiple of 3 written on it: the box with 3. The total number of balls contained in these boxes is 0.

Thus, the condition is satisfied, so this set of choices is good.

Sample Input 2

5
0 0 0 0 0

Sample Output 2

0

Putting nothing in the boxes can be a good set of choices.

Solution in Rust (1.15.1) (judge verdict: Accepted)

fn main() {
    let n: usize = read();
    let a: Vec<usize> = read_vec();
    let mut ball: Vec<bool> = vec![false;n];
    for i in (1..n+1).rev() {
        let mut f = false;
        let mut m = i;
        loop {
            m += i; if m > n { break; }
            f ^= ball[m-1];
        }
        ball[i-1] = f ^ (a[i-1] == 1);
    }
    let mut ans: Vec<usize> = vec![];
    for (i,b) in ball.iter().enumerate() {
        if *b { ans.push(i+1); }
    }
    println!("{}", ans.len() );
    for i in ans.iter() {
        print!("{} ", *i);
    }
}

fn get_line() -> String {
    let mut buf = String::new();
    std::io::stdin().read_line(&mut buf).ok();
    buf.trim().to_owned()
}

fn read<T: std::str::FromStr>() -> T{
    get_line().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T>{
    get_line().split_whitespace()
        .map(|e| e.parse().ok().unwrap()).collect()
}