import java.util.Scanner;
public class Main{
	private static Scanner sc=new Scanner(System.in);
	public static void main(String args[])throws Exception{
		int n=sc.nextInt(),a=sc.nextInt(),sum=0;
		for(int i=0;i<n;i++){
			sum+=sc.nextInt();
		}double abe=sum*1.0/n;
		if(abe == a)System.out.println("YES");
		else System.out.println("NO");
	}
}