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[] x = new long[n];
		for(int i = 0 ; i < n ; i++) x[i] = sc.nextInt();
		long ans = 0;
		for(int i = 0 ; i < n ; i++) {
			ans += x[i];
		}
		if(ans == a * n) {
			System.out.println("YES");
		} else {
			System.out.println("NO");
		}
	}
}