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

public class No476 {

	public static void main(String[] args) {
		try{
			BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
			String[] str = br.readLine().split(" ");
			int N = Integer.parseInt(str[0]);
			double maiAns = Double.parseDouble(str[1]);
			String[] str2 = br.readLine().split(" ");
			long[] num = new long[N];
			long sum = 0;
			for(int i=0; i < N; i++){
				num[i] = Integer.parseInt(str2[i]);
				sum += num[i];
			}
			double ave = (double)sum / N;
			if(maiAns == ave) System.out.println("YES");
			else System.out.println("NO");
		}catch(IOException e){
			e.getStackTrace();
		}catch(NumberFormatException e){
			e.getStackTrace();
		}
	}

}