import java.util.*; public class Main { static long mod = (long)Math.pow(10,6); public static void main(String[] args) { Scanner sc = new Scanner(System.in); int N = sc.nextInt(); int a = sc.nextInt(); long sum=0; for(int i=0; i<N; i++){ int tmp = sc.nextInt(); sum+=tmp; } double ave = sum/(double)N; if(ave==a){ System.out.println("YES"); }else{ System.out.println("NO"); } } }