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