import java.util.*; 

public class test {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long n = sc.nextInt();
		long a = sc.nextInt();
		long x = 0;
		
		for(int i=0; i<n; i++){
			x += sc.nextInt();
		}
		
		if((double)x / n == a){
			System.out.println("YES");
		}
		else{
			System.out.println("NO");
		}
	}
}