using System;
using System.Text;
using System.Linq;

namespace ConsoleApp11
{
    class Program
    {
        static void Main(string[] args)
        {
            decimal average = 0;
            long sum = 0;

            var input = Console.ReadLine().Trim().Split(' ');
            var input1 = Console.ReadLine().Split(' ');

            long n = long.Parse(input[0]);
            long a = long.Parse(input[1]);

            long[] x = new long[n];

            for(int i = 0; i < n; i++)
            {
                x[i] = long.Parse(input1[i]);
            }

            for(long i = 0; i < n; i++)
            {
                sum += x[i];
            }

            average = (decimal)sum / x.Length;

            if(average == a)
            {
                Console.WriteLine("YES");
            }
            else
            {
                Console.WriteLine("NO");
            }
        }        
    }
}