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