import java.util.*;

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

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