import java.util.*;
class No476{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		int N = sc.nextInt();
		int a = sc.nextInt();
		int sum = 0;
		double ave = 0;
		
		for(int i=0; i<N; i++){
			int No = sc.nextInt();
			sum += No;
			ave = sum/N;
		}
		
		if(a == ave){
			System.out.println("YES");
		}else{
			System.out.println("NO");
		}
	}
}