### 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.

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.