import java.util.*;

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

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