using System;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        var input = Console.ReadLine().Split(' ');
        var ans = int.Parse(input[1]);
        var list = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToList();
        var avg = list.Average();

        var msg = (avg == ans) ? "YES" : "NO";
        Console.WriteLine(msg);
    }
}