import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		char[] s = sc.next().toCharArray();
		sc.close();

		Set<Character> set = new HashSet<>();
		for (int i = 0; i < n; i++) {
			if (!set.add(s[i])) {
				System.out.println("Yes");
				return;
			}
		}
		System.out.println("No");
	}
}