import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        int a = scan.nextInt();
        int ans=0;
        boolean flg=true;
        for(int i=0;i<a;i++){
            int c=scan.nextInt();
            if(i+1!=c){
                ans+=1;
                if(ans==3){flg=false;break;}
            }
        }
        String b = flg?"YES":"NO";
        System.out.println(b);
    }
}
/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