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.

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.

Constraints

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

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.

见题面 Input 部分

见题面 Output 部分