
import java.util.Scanner;



public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int con = 0;
		for (int i = 1; i < N+1; i++) {

			if (i != sc.nextInt()) {
				con++;
			}
		}

		if (con == 2 || con==0) {
			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();
		int con = 0;
		for (int i = 1; i < N+1; i++) {

			if (i != sc.nextInt()) {
				con++;
			}
		}

		if (con == 2 || con==0) {
			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();
		int con = 0;
		for (int i = 1; i < N+1; i++) {

			if (i != sc.nextInt()) {
				con++;
			}
		}

		if (con == 2 || con==0) {
			System.out.println("YES");
		} else {
			System.out.println("NO");
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int con = 0;
		for (int i = 1; i < N+1; i++) {

			if (i != sc.nextInt()) {
				con++;
			}
		}

		if (con == 2 || con==0) {
			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 con = 0; con 0 for (int i = 1; i < N+1; i++) {

			if (i != sc.nextInt()) {
				con++;
			}
		} int i = 1; int i = 1; i 1 i < N+1 i N+1 N 1 i++ i++ i {

			if (i != sc.nextInt()) {
				con++;
			}
		} {

			if (i != sc.nextInt()) {
				con++;
			}
		} if (i != sc.nextInt()) {
				con++;
			} i != sc.nextInt() i sc.nextInt() sc.nextInt sc {
				con++;
			} con++ con if (con == 2 || con==0) {
			System.out.println("YES");
		} else {
			System.out.println("NO");
		} con == 2 || con==0 con == 2 con 2 con==0 con 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 sc = new Scanner(System.in);
		int N = sc.nextInt();
		int con = 0;
		for (int i = 1; i < N+1; i++) {

			if (i != sc.nextInt()) {
				con++;
			}
		}

		if (con == 2 || con==0) {
			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();
		int con = 0;
		for (int i = 1; i < N+1; i++) {

			if (i != sc.nextInt()) {
				con++;
			}
		}

		if (con == 2 || con==0) {
			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();
		int con = 0;
		for (int i = 1; i < N+1; i++) {

			if (i != sc.nextInt()) {
				con++;
			}
		}

		if (con == 2 || con==0) {
			System.out.println("YES");
		} else {
			System.out.println("NO");
		}
	}

}