import java.util.*;

public class Main {

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

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

public class Main {

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