import java.util.Scanner;

class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String[] str=sc.nextLine().split(" ");
		int[] num1=new int[2];
		num1[0]=Integer.parseInt(str[0]);
		num1[1]=Integer.parseInt(str[1]);
		str=sc.nextLine().split(" ");
		long[] num2=new long[num1[0]];
		sc.close();
		long sum=0;
		for(int i=0;i<num2.length;i++){
			sum+=Long.parseLong(str[i]);
		}
		if(num1[1]==(double)sum/num2.length){
			System.out.println("YES");
		}else{
			System.out.println("NO");
		}
	}
}