import java.util.*;
import java.lang.*;
import java.io.*;

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

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