Problem:
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.

Solution in JavaScript (Node.js 12.16.1) (judge verdict: Wrong Answer)

const main = input => {
  const inputs = input.trim().split('\n')

  const N = parseInt(inputs[0])
  const sequence = inputs[1].split(' ')

  const sortedSample = sequence.slice().sort()

  let diff = 0
  for (let i = 0; i < N; i++) {
    if (sequence[i] !== sortedSample[i]) {
      diff++
    }
  }

  diff === 2 || diff === 0 ? console.log('YES') : console.log('NO')

}
// 標準入力
main(require("fs").readFileSync("/dev/stdin", "utf8"))