import java.util.*;

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

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