import java.io.PrintWriter;
import java.util.*;
import java.util.concurrent.SynchronousQueue;

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

	static void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}
}