import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    long a = sc.nextLong();
    long sum = 0;
    for(int i = 0; i < n; i++) {
      sum += sc.nextLong();
    }
    String ans = "NO";
    if(sum == a * n) ans = "YES";
    System.out.println(ans);
  }
}