# Home

Score : $200$ points

### Problem Statement

We have a sequence $p$ = {$p_1,\ p_2,\ ...,\ p_N$} which is a permutation of {$1,\ 2,\ ...,\ N$}.

You can perform the following operation at most once: choose integers $i$ and $j$ $(1 \leq i < j \leq N)$, and swap $p_i$ and $p_j$. Note that you can also choose not to perform it.

Print YES if you can sort $p$ in ascending order in this way, and NO otherwise.

### Constraints

• All values in input are integers.
• $2 \leq N \leq 50$
• $p$ is a permutation of {$1,\ 2,\ ...,\ N$}.

### Input

Input is given from Standard Input in the following format:

$N$
$p_1$ $p_2$ $...$ $p_N$


### Output

Print YES if you can sort $p$ in ascending order in the way stated in the problem statement, and NO otherwise.

### Sample Input 1

5
5 2 3 4 1


### Sample Output 1

YES


You can sort $p$ in ascending order by swapping $p_1$ and $p_5$.

### Sample Input 2

5
2 4 3 5 1


### Sample Output 2

NO


In this case, swapping any two elements does not sort $p$ in ascending order.

### Sample Input 3

7
1 2 3 4 5 6 7


### Sample Output 3

YES


$p$ is already sorted in ascending order, so no operation is needed.