import java.util.*;
import java.io.*;

class Main{
  public static void main(String[] args){
   	Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    Integer p[] = new Integer[n];
    for(int i=0;i<n;i++){
      p[i] = sc.nextInt();
    }
    int d = 0;
    Integer q[] = new Integer[n];
    for(int i=0;i<n;i++){
      q[i] = i+1;
    }



    for(int i=0;i < n ;i++){
      if(p[i] != q[i]){
        d ++;
      }
    }
    if(d == 2 || d == 0){
      System.out.println("YES");
    }else{
      System.out.println("NO");
    }

    }

  }

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz