using System;

class Program
{
    static void Main()
    {
        
        string S = Console.ReadLine();

        if (S.Length != 3)
        {
            Console.WriteLine("No");
            return;
        }

        if ((S[0] == S[1]) && (S[0] != S[2]))
        {
            Console.WriteLine("Yes");
        }
        else 
        {
            Console.WriteLine("No");
        }
    }
}