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 {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int N =sc.nextInt();
        ArrayList<Integer> List = new ArrayList<>();
        int num_list [] = new int[N];
        ArrayList<Integer> OPT = new ArrayList<>();
        int opt_num =0;
        for(int i=0;i<N;i++){
            int num=sc.nextInt();
            List.add(num);
            if(num==0) num_list[i]=0;
            else{
                for(int j=i;j>=0;j--){
                    if((i+1)%(j+1)==0) {
                        num_list[j]++;
                    }
                }
            }
        }
        for(int i=0;i<N;i++){
            if((i+1)*2<=N){
                if((num_list[i]%2)!=List.get(i)){
                    OPT.add(i+1);
                    opt_num++;
                }
                else if(num_list[i]==1&&List.get(i)==1){
                    OPT.add(i+1);
                    opt_num++;
                }
            }
            else if(List.get(i)==1) {
                OPT.add(i+1);
                opt_num++;
            }
        }
        System.out.println(opt_num);
        for(int i=0;i<OPT.size();i++){
            System.out.print(OPT.get(i));
            if(i<N-1) System.out.print(" ");
        }
        System.out.println();
    }
}