import java.util.Scanner;

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 counter = 0;
    boolean ans = true;
    for(int i = 0;i < n;i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } 
    }
    if(ans){
      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[] p = new int[n];
    int counter = 0;
    boolean ans = true;
    for(int i = 0;i < n;i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } 
    }
    if(ans){
      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 counter = 0;
    boolean ans = true;
    for(int i = 0;i < n;i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } 
    }
    if(ans){
      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 counter = 0;
    boolean ans = true;
    for(int i = 0;i < n;i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } 
    }
    if(ans){
      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 counter = 0; counter 0 boolean ans = true; ans true for(int i = 0;i < n;i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } 
    } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } 
    } {
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } 
    } p[i] = sc.nextInt() p[i] p i sc.nextInt() sc.nextInt sc if(p[i] != i + 1){
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } p[i] != i + 1 p[i] p i i + 1 i 1 {
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } counter++ counter if(counter == 3){
          ans = false;
          break;
        } counter == 3 counter 3 {
          ans = false;
          break;
        } ans = false ans false break; if(ans){
      System.out.println("YES");
    }else{
      System.out.println("NO");
    } ans {
      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 counter = 0;
    boolean ans = true;
    for(int i = 0;i < n;i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } 
    }
    if(ans){
      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 counter = 0;
    boolean ans = true;
    for(int i = 0;i < n;i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } 
    }
    if(ans){
      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[] p = new int[n];
    int counter = 0;
    boolean ans = true;
    for(int i = 0;i < n;i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        counter++;
        if(counter == 3){
          ans = false;
          break;
        }
      } 
    }
    if(ans){
      System.out.println("YES");
    }else{
      System.out.println("NO");
    }
  }
}
