import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        sc.nextLine();

        int p[]=new int[N];
        for (int i=0;i<N;i++){
            p[i]=sc.nextInt();
        }
        int count=0;

        for (int i=0; i<N;i++){
            if (p[i] != i+1){
                count++;
            }
        }
        if (count==0||count==2){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        }


    }




} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        sc.nextLine();

        int p[]=new int[N];
        for (int i=0;i<N;i++){
            p[i]=sc.nextInt();
        }
        int count=0;

        for (int i=0; i<N;i++){
            if (p[i] != i+1){
                count++;
            }
        }
        if (count==0||count==2){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        }


    }




} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        sc.nextLine();

        int p[]=new int[N];
        for (int i=0;i<N;i++){
            p[i]=sc.nextInt();
        }
        int count=0;

        for (int i=0; i<N;i++){
            if (p[i] != i+1){
                count++;
            }
        }
        if (count==0||count==2){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        }


    } main {
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        sc.nextLine();

        int p[]=new int[N];
        for (int i=0;i<N;i++){
            p[i]=sc.nextInt();
        }
        int count=0;

        for (int i=0; i<N;i++){
            if (p[i] != i+1){
                count++;
            }
        }
        if (count==0||count==2){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        }


    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N= sc.nextInt(); N sc.nextInt() sc.nextInt sc sc.nextLine() sc.nextLine sc int p[]=new int[N]; p new int[N] N for (int i=0;i<N;i++){
            p[i]=sc.nextInt();
        } int i=0; int i=0; i 0 i<N i N i++ i++ i {
            p[i]=sc.nextInt();
        } {
            p[i]=sc.nextInt();
        } p[i]=sc.nextInt() p[i] p i sc.nextInt() sc.nextInt sc int count=0; count 0 for (int i=0; i<N;i++){
            if (p[i] != i+1){
                count++;
            }
        } int i=0; int i=0; i 0 i<N i N i++ i++ i {
            if (p[i] != i+1){
                count++;
            }
        } {
            if (p[i] != i+1){
                count++;
            }
        } if (p[i] != i+1){
                count++;
            } p[i] != i+1 p[i] p i i+1 i 1 {
                count++;
            } count++ count if (count==0||count==2){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        } count==0||count==2 count==0 count 0 count==2 count 2 {
            System.out.println("YES");
        } System.out.println("YES") System.out.println System.out System System.out "YES" {
            System.out.println("NO");
        } System.out.println("NO") System.out.println System.out System System.out "NO" String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        sc.nextLine();

        int p[]=new int[N];
        for (int i=0;i<N;i++){
            p[i]=sc.nextInt();
        }
        int count=0;

        for (int i=0; i<N;i++){
            if (p[i] != i+1){
                count++;
            }
        }
        if (count==0||count==2){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        }


    }




} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        sc.nextLine();

        int p[]=new int[N];
        for (int i=0;i<N;i++){
            p[i]=sc.nextInt();
        }
        int count=0;

        for (int i=0; i<N;i++){
            if (p[i] != i+1){
                count++;
            }
        }
        if (count==0||count==2){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        }


    }




} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N= sc.nextInt();
        sc.nextLine();

        int p[]=new int[N];
        for (int i=0;i<N;i++){
            p[i]=sc.nextInt();
        }
        int count=0;

        for (int i=0; i<N;i++){
            if (p[i] != i+1){
                count++;
            }
        }
        if (count==0||count==2){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        }


    }




}
