package no476;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		long a = sc.nextLong();
		long sum = 0;
		for(int i=0;i<n;i++) {
			sum += sc.nextLong();
		}
		System.out.println(a * n == sum ? "YES" : "NO");
		
	}

}