import java.util.*;

class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] p = 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(cnt == 0 || cnt == 2 ?"YES":"NO");
    }
} import java.util.*; util.* java class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] p = 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(cnt == 0 || cnt == 2 ?"YES":"NO");
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] p = 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(cnt == 0 || cnt == 2 ?"YES":"NO");
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] p = 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(cnt == 0 || cnt == 2 ?"YES":"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 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++;
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            if(p[i] != i+1)
            cnt++;
        } {
            if(p[i] != i+1)
            cnt++;
        } if(p[i] != i+1)
            cnt++; p[i] != i+1 p[i] p i i+1 i 1 cnt++ cnt System.out.println(cnt == 0 || cnt == 2 ?"YES":"NO") System.out.println System.out System System.out cnt == 0 || cnt == 2 ?"YES":"NO" cnt == 0 || cnt == 2 cnt == 0 cnt 0 cnt == 2 cnt 2 "YES" "NO" String[] args args
import java.util.*;

class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] p = 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(cnt == 0 || cnt == 2 ?"YES":"NO");
    }
}