import java.util.*;
import java.lang.*;
 
public class Main {
    public static void main(String[] args) {

        Scanner sc  = new Scanner(System.in); 

        long n = Long.parseLong(sc.next());
        long a = Long.parseLong(sc.next());

        float ans = 0;

        for(int i=0;i<n;i++){
            ans += Long.parseLong(sc.next());
        }
        
        if(ans/n==a) System.out.println("YES");
        else         System.out.println("NO");


        System.out.println();
    }

}