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 flg = 0;
    String ans = "NO";

    for(int i = 0; i < n; i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        flg += 1;
      }
    }

    if(flg == 0 || flg == 2){
      ans = "YES";
    }

    System.out.println(ans);
  }
} 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 flg = 0;
    String ans = "NO";

    for(int i = 0; i < n; i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        flg += 1;
      }
    }

    if(flg == 0 || flg == 2){
      ans = "YES";
    }

    System.out.println(ans);
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);

    int n = sc.nextInt();
    int[] p = new int[n];
    int flg = 0;
    String ans = "NO";

    for(int i = 0; i < n; i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        flg += 1;
      }
    }

    if(flg == 0 || flg == 2){
      ans = "YES";
    }

    System.out.println(ans);
  } main {
    Scanner sc = new Scanner(System.in);

    int n = sc.nextInt();
    int[] p = new int[n];
    int flg = 0;
    String ans = "NO";

    for(int i = 0; i < n; i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        flg += 1;
      }
    }

    if(flg == 0 || flg == 2){
      ans = "YES";
    }

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

    for(int i = 0; i < n; i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        flg += 1;
      }
    }

    if(flg == 0 || flg == 2){
      ans = "YES";
    }

    System.out.println(ans);
  }
} 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 flg = 0;
    String ans = "NO";

    for(int i = 0; i < n; i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        flg += 1;
      }
    }

    if(flg == 0 || flg == 2){
      ans = "YES";
    }

    System.out.println(ans);
  }
} 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 flg = 0;
    String ans = "NO";

    for(int i = 0; i < n; i++){
      p[i] = sc.nextInt();
      if(p[i] != i + 1){
        flg += 1;
      }
    }

    if(flg == 0 || flg == 2){
      ans = "YES";
    }

    System.out.println(ans);
  }
}
