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 + 1];
        String res = "YES";
        for(int i = 1; i <= n; i++) p[i] = sc.nextInt();
        for(int i = 1; i <= n; i++) {
            if(i != p[i] && p[p[i]] == i) {
                p[p[i]] = p[i];
                p[i] = i;
                break;
            }
        }
        for(int i = 1; i < n; i++) if(p[i] > p[i + 1]) res = "NO";
        System.out.println(res);
    }
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz