package yukicodercontest155;

import java.util.*;
public class A{
	static Scanner s = new Scanner(System.in);
	public static void main(String[] args) {
		int n=s.nextInt();
		double a=s.nextDouble();
		long l=0;
		for(int i=0;i<n;i++) l+=s.nextLong();

		System.out.println((a==l*1.0/n)?"YES":"NO");
	}
}