import java.util.Scanner;

public class Main {
	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
		
		int[] numbers = new int[N];
		for (int i = 0; i < N; i++) {
			numbers[i] = scan.nextInt();
		}
		
		int count = 0;
		for (int i = 1; i <= numbers.length; i++) {
			if (numbers[i - 1] == i) {
				count++;
			}
		}
		
		if (count >= (N - 2)) {
			System.out.println("YES");
		} else {
			System.out.println("NO");
		}
		
	}
}
/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