import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class No00000476_Main {
	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	public static void main(String[] args) throws IOException {
		String[] t = br.readLine().split(" ");
		int n = Integer.parseInt(t[0]);
		String[] x = br.readLine().split(" ");
		int sum = 0;
		for(int i = 0; i < n; i++) sum += Integer.parseInt(x[i]);
		System.out.println(n * Integer.parseInt(t[1]) == sum ? "YES" : "NO");
	}
}