import java.util.Scanner;

public class Avg {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		double n = sc.nextLong();
		double a = sc.nextLong();
		double sum = 0;
		for(int i = 0; i < n; i++){
			sum += sc.nextDouble();
		}

		sc.close();

		System.out.println(sum / n == a ? "YES" : "NO");

	}

}