import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] p = new int[n];
        int[] p2 = new int[n];
        int cnt =0;
        
        for(int i = 0;i<n;i++){
            p[i] = sc.nextInt();
        }



        for(int i = 0;i<n;i++){
           if(p[i]!=i+1){
               cnt++;
               //System.out.println(p[i]);
           }
        }

        //System.out.println(cnt);
        if(cnt==0 || cnt==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[] p = new int[n];
        int[] p2 = new int[n];
        int cnt =0;
        
        for(int i = 0;i<n;i++){
            p[i] = sc.nextInt();
        }



        for(int i = 0;i<n;i++){
           if(p[i]!=i+1){
               cnt++;
               //System.out.println(p[i]);
           }
        }

        //System.out.println(cnt);
        if(cnt==0 || cnt==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[] p = new int[n];
        int[] p2 = new int[n];
        int cnt =0;
        
        for(int i = 0;i<n;i++){
            p[i] = sc.nextInt();
        }



        for(int i = 0;i<n;i++){
           if(p[i]!=i+1){
               cnt++;
               //System.out.println(p[i]);
           }
        }

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

    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] p = new int[n];
        int[] p2 = new int[n];
        int cnt =0;
        
        for(int i = 0;i<n;i++){
            p[i] = sc.nextInt();
        }



        for(int i = 0;i<n;i++){
           if(p[i]!=i+1){
               cnt++;
               //System.out.println(p[i]);
           }
        }

        //System.out.println(cnt);
        if(cnt==0 || cnt==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[] p = new int[n]; p new int[n] n int[] p2 = new int[n]; p2 new int[n] n int cnt =0; cnt 0 for(int i = 0;i<n;i++){
            p[i] = sc.nextInt();
        } int i = 0; int i = 0; i 0 i<n i n i++ i++ i {
            p[i] = sc.nextInt();
        } {
            p[i] = sc.nextInt();
        } p[i] = sc.nextInt() p[i] p i sc.nextInt() sc.nextInt sc for(int i = 0;i<n;i++){
           if(p[i]!=i+1){
               cnt++;
               //System.out.println(p[i]);
           }
        } int i = 0; int i = 0; i 0 i<n i n i++ i++ i {
           if(p[i]!=i+1){
               cnt++;
               //System.out.println(p[i]);
           }
        } {
           if(p[i]!=i+1){
               cnt++;
               //System.out.println(p[i]);
           }
        } if(p[i]!=i+1){
               cnt++;
               //System.out.println(p[i]);
           } p[i]!=i+1 p[i] p i i+1 i 1 {
               cnt++;
               //System.out.println(p[i]);
           } cnt++ cnt if(cnt==0 || cnt==2){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        } cnt==0 || cnt==2 cnt==0 cnt 0 cnt==2 cnt 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[] p = new int[n];
        int[] p2 = new int[n];
        int cnt =0;
        
        for(int i = 0;i<n;i++){
            p[i] = sc.nextInt();
        }



        for(int i = 0;i<n;i++){
           if(p[i]!=i+1){
               cnt++;
               //System.out.println(p[i]);
           }
        }

        //System.out.println(cnt);
        if(cnt==0 || cnt==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[] p = new int[n];
        int[] p2 = new int[n];
        int cnt =0;
        
        for(int i = 0;i<n;i++){
            p[i] = sc.nextInt();
        }



        for(int i = 0;i<n;i++){
           if(p[i]!=i+1){
               cnt++;
               //System.out.println(p[i]);
           }
        }

        //System.out.println(cnt);
        if(cnt==0 || cnt==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[] p = new int[n];
        int[] p2 = new int[n];
        int cnt =0;
        
        for(int i = 0;i<n;i++){
            p[i] = sc.nextInt();
        }



        for(int i = 0;i<n;i++){
           if(p[i]!=i+1){
               cnt++;
               //System.out.println(p[i]);
           }
        }

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

    }
}
