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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.*;

public class Main {
    static Scanner scanner = new Scanner(System.in);

    static int n;
    static boolean[] a;
    static Boolean[] memo;
    static int count = 0;
    public static void main(String[]$) {
        n = scanner.nextInt();
        a = new boolean[n];
        memo = new Boolean[n];
        for (int i = 0; i < n; i++) {
            a[i] = scanner.nextInt() == 1;
        }
        for (int i = 1; i <= n; i++) {
            f(i);
        }
        for (int i = 0; i < n; i++) {
            if (memo[i]) {
                System.out.println(i + 1);
            }
        }
    }

    static boolean f(int i) {
        if (memo[i - 1] != null) {
            return memo[i - 1];
        }
        boolean b = a[i - 1];
        int j = 2;
        while (i * j <= n) {
            if (f(i * j)) {
                b = !b;
            }
            j++;
        }
        if (b) {
            count++;
        }
        return memo[i - 1] = b;
    }
}