import java.util.ArrayList;
import java.util.Scanner;

public class No476 {

    public static void main(String[] args) {
	Scanner s = new Scanner(System.in);
	int N = s.nextInt();
	int A = s.nextInt();
	ArrayList<Integer> list = new ArrayList<>();
	for(int i=0;i<N;i++){
	    list.add(s.nextInt());
	}
	double ave; int sum = 0;
	for(int i :list){
	    sum += i;
	}
	ave = (double)sum / N;
	if(ave == A){
	    System.out.println("YES");
	}else{
	    System.out.println("NO");
	}
    }

}