import java.util.*;

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