import java.math.BigDecimal;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = Integer.parseInt(sc.next());
        BigDecimal A = new BigDecimal(sc.next());

        BigDecimal sum = new BigDecimal("0");
        for (int i = 0; i < N; i++) {
            sum = sum.add(new BigDecimal(sc.next()));
        }

        BigDecimal avg = sum.divide(new BigDecimal(N));

        if (A.equals(avg)) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
}