import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();

        int answer = sc.nextInt();

        int sum = 0;

        for (int i = 0; i < n; i++) {
            sum += sc.nextInt();
        }

        System.out.println(sum == answer * n ? "YES" : "NO");

    }

}