import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		long a = scan.nextLong();
		long sum = 0;
		for(int i = 0; i < n; i++) {
			sum +=  scan.nextLong();
		}
		scan.close();
		float m = (float)sum / n;
		if(m == a) {
			System.out.println("YES");
		}else {
			System.out.println("NO");
		}
	}
}