import java.util.Scanner;
class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int cnt = 0;
    for(int i=1; i<=N; i++){
      int tmp = sc.nextInt();
      if(i != tmp){
        cnt++;
      }
    }
    if(cnt == 0 || cnt == 2){
      System.out.print("YES");
    }else{
      System.out.print("NO");
    }
  }
}

         import java.util.Scanner; Scanner java.util class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int cnt = 0;
    for(int i=1; i<=N; i++){
      int tmp = sc.nextInt();
      if(i != tmp){
        cnt++;
      }
    }
    if(cnt == 0 || cnt == 2){
      System.out.print("YES");
    }else{
      System.out.print("NO");
    }
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int cnt = 0;
    for(int i=1; i<=N; i++){
      int tmp = sc.nextInt();
      if(i != tmp){
        cnt++;
      }
    }
    if(cnt == 0 || cnt == 2){
      System.out.print("YES");
    }else{
      System.out.print("NO");
    }
  } main {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int cnt = 0;
    for(int i=1; i<=N; i++){
      int tmp = sc.nextInt();
      if(i != tmp){
        cnt++;
      }
    }
    if(cnt == 0 || cnt == 2){
      System.out.print("YES");
    }else{
      System.out.print("NO");
    }
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int cnt = 0; cnt 0 for(int i=1; i<=N; i++){
      int tmp = sc.nextInt();
      if(i != tmp){
        cnt++;
      }
    } int i=1; int i=1; i 1 i<=N i N i++ i++ i {
      int tmp = sc.nextInt();
      if(i != tmp){
        cnt++;
      }
    } {
      int tmp = sc.nextInt();
      if(i != tmp){
        cnt++;
      }
    } int tmp = sc.nextInt(); tmp sc.nextInt() sc.nextInt sc if(i != tmp){
        cnt++;
      } i != tmp i tmp {
        cnt++;
      } cnt++ cnt if(cnt == 0 || cnt == 2){
      System.out.print("YES");
    }else{
      System.out.print("NO");
    } cnt == 0 || cnt == 2 cnt == 0 cnt 0 cnt == 2 cnt 2 {
      System.out.print("YES");
    } System.out.print("YES") System.out.print System.out System System.out "YES" {
      System.out.print("NO");
    } System.out.print("NO") System.out.print System.out System System.out "NO" String[] args args
import java.util.Scanner;
class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int cnt = 0;
    for(int i=1; i<=N; i++){
      int tmp = sc.nextInt();
      if(i != tmp){
        cnt++;
      }
    }
    if(cnt == 0 || cnt == 2){
      System.out.print("YES");
    }else{
      System.out.print("NO");
    }
  }
}

        
