import java.util.*;

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

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