import java.util.*;

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