import java.util.*;

public class Main{
  public static void main(String[] args){
    double sum = 0;
    Scanner sc = new Scanner(System.in);
    int num = sc.nextInt();
    double ans = sc.nextDouble();
    for(int i=0;i<num;i++){
      sum += sc.nextDouble();
    }
    if(sum/num == ans)System.out.println("YES");
    else System.out.println("NO");
  }
}