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 Python (3.4.3) (judge verdict: Wrong Answer)

def primes(x):
  is_prime = [True] * (x + 1)
  is_prime[0] = False
  is_prime[1] = False
  for i in range(2, int(x**0.5) + 1):
    if not is_prime[i]:
      continue
    for j in range(i * 2, x + 1, i):
      is_prime[j] = False
  return [i for i in range(x + 1) if is_prime[i]]

n=int(input())
P=primes(n)
pp=len(P)
A=[int(i) for i in input().split()]
Ans=[]
C=[False]*n
for i in reversed(range(n)):
  if A[i]==1:    
    if 2*(i+1)>n:
      Ans.append(i+1)
      C[i]=True
    else:
      c=1
      j=0
      while j<pp and P[j]*(i+1)<=n:
        if C[P[j]*(i+1)-1]==True:
          c^=1
        j+=1
      if c==1:
        Ans.append(i+1)
        C[i]=True
  elif A[i]==0:    
    c=0
    j=0
    while j<pp and P[j]*(i+1)<=n:
      if C[P[j]*(i+1)-1]==True:
        c^=1
      j+=1
    if c==0:
      Ans.append(i+1)
      C[i]=True
if len(Ans)==0:
  print(0)
else:
  print(len(Ans))
  Ans.sort()
  print(*Ans)