import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		double n =sc.nextDouble();
		double a = sc.nextDouble();
		long total = 0;
		for (int i=0; i<n; i++) {
			total += sc.nextInt();
		}
		double average = total/n;
		System.out.println(average==a?"YES":"NO");
	}
}