import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

    	Scanner sc = new Scanner(System.in);
    	int num = sc.nextInt();
    	int av = sc.nextInt();
    	int ar[] = new int[num];
    	int ans = 0;
    	for(int i=0;i<num;i++){
    		ans += sc.nextInt();
    	}
    	int ret = ans/num;

    	if(ret==av){
    		System.out.println("YES");
    	}else{
    		System.out.println("NO");
    	}
    }

}