import java.util.Scanner;

public class Main{
  public static void main(String args[]){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int[] p = new int[n];
    int counter = 0;
    boolean ans = true;
    for(int i = 0;i < n;i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } 
    }
    if(ans){
      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