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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.*;
import java.util.Arrays;
class Main
{
  public static void main(String args[])
  {
    Scanner sc=new Scanner(System.in);
    int n=sc.nextInt();
    int a[]=new int[n];
    for(int i=0;i<n;i++)
      a[i]=sc.nextInt();
    int b[]=new int[n];
    b=Arrays.copyOfRange(a,0,n);
    Arrays.sort(b);
    int t=0;
    for(int i=0;i<n;i++)
      if((a[i]-b[i])<0)
        t++;
    if(t==0||t==2)
      System.out.println("YES");
    else 
      System.out.println("NO");
  }
}