using System.Numerics;

public class Program
{
    public static void Main()
    {

        //BigInteger num = BigInteger.Parse(Console.ReadLine() ?? string.Empty);
        int num = int.Parse(Console.ReadLine() ?? string.Empty);
        //string[] str = (Console.ReadLine() ?? string.Empty).Trim().Split(' ');
        string str = Console.ReadLine() ?? string.Empty;

        for (int i = 0; i < num; i++)
        {
            int index = str.LastIndexOf(str[i]);
            if (index != -1&&index != i)
            {
                Console.WriteLine("Yes");
                return;
            }

        }
        Console.WriteLine("No");



    }

}