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 C (Clang 3.8.0) (judge verdict: Accepted)

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>
#include <string.h>
#include <math.h>

int main (void)
{
    intmax_t N, a[(int)2e5 + 1];
    intmax_t box[(int)2e5 + 1] = {0}, M = 0;

    scanf("%jd", &N);
    for (size_t i = 1; i <= N; i++) {
        scanf("%jd", &a[i]);
    }

    for (size_t i = N; i > (N / 2); i--) {
        if (a[i]) {
            M++;
            box[i] = 1;
        }
    }
    for (size_t i = (N / 2); i > 0; i--) {
        intmax_t balls = 0;
        for (size_t j = (i * 2); j <= N; j += i) {
            balls += box[j];
        }
        if (a[i] != (balls % 2)) {
            M++;
            box[i] = 1;
        }
    }

    printf("%jd\n", M);
    if (M <= 0) return 0;
    for (size_t i = 1; i <= N; i++) {
        if (box[i]) {
            printf("%zd", i);
            if (--M) {
                printf(" ");
            } else {
                printf("\n");
                break;
            }
        }
    }

    return 0;
}