import java.util.Scanner;

public class Ex1
{
	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		int index = scan.nextInt();
		int ave = scan.nextInt();
		int i = index;
		int sum=0;
		while(i-- != 0){
			sum += scan.nextInt();
		}
		
		if(sum == ave*index)
			System.out.println("yes");
		else 
			System.out.println("no");
	}
}