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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include<bits/stdc++.h>
#define N 200005
using namespace std;
bool cur1;
int n;
int a[N],dp[N];
int stk[N],top;
inline void Rd(int &res){
	char c;res=0;
	while(c=getchar(),c<48);
	do res=(res<<3)+(res<<1)+(c^48);
	while(c=getchar(),c>47);
	return;
}
bool cur2;
int main(){
//	printf("%lf MB\n",(&cur2-&cur1)/1024.0/1024);
	Rd(n);
	for(int i=1;i<=n;i++)Rd(a[i]);
	bool flag=0;
	for(int i=n;i>=1;i--){
		int sm=0;
		for(int j=i+i;j<=n;j+=i)sm^=dp[j];
		if(a[i]==sm)dp[i]=0;
		else dp[i]=1,stk[++top]=i;
	}
	if(flag)puts("-1");
	else{
		printf("%d\n",top);
		for(int i=top;i>=1;i--)printf("%d ",stk[i]);puts("");
	}
	return 0;
}