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");
        }
    }
}