Problem Statement

There are N people whose IDs are $1, 2, \ldots$, and N.
Each of person $1, person 2, \ldots$, and person N performs the following action once in this order:

• If person i's ID has not been called out yet, call out person A_i's ID.

Enumerate the IDs of all the people whose IDs are never called out until the end in ascending order.

Input

The input is given from Standard Input in the following format:
N
$A_1 A_2 \ldots A_N$

Output

Enumerate the IDs of all the people whose IDs are not called out until the end in ascending order in the following format:
K
$X_1 X_2 \ldots X_K$

In other words, the first line should contain the number of people, K, whose IDs are never called out until the end;
the second line should contain the sequence $(X_1, X_2, \ldots, X_K)$ of IDs of such people in ascending order, with spaces in between.

Constraints

• $2 \leq N \leq 2 \times 10^5$
• $1 \leq A_i \leq N$
• $A_i \neq i$
• All values in the input are integers.

Sample Input 1

5
3 1 4 5 4

Sample Output 1

2
2 4

The five people's actions are as follows.

• Person 1's ID has not been called out yet, so person 1 calls out person 3's ID.
• Person 2's ID has not been called out yet, so person 2 calls out person 1's ID.
• Person 3's ID has already been called out by person 1, so nothing happens.
• Person 4's ID has not been called out yet, so person 4 calls out person 5's ID.
• Person 5's ID has already been called out by person 4, so nothing happens.

Therefore, person 2 and 4's IDs are not called out until the end.

Sample Input 2

20
9 7 19 7 10 4 13 9 4 8 10 15 16 3 18 19 12 13 2 12

Sample Output 2

10
1 2 5 6 8 11 14 17 18 20

见题面 Input 部分

见题面 Output 部分