#include <iostream>
using namespace std;
 
int main(){
	int n, a;
	cin >> n >> a;
	long all = n * a;
	for(int i = 0; i < n; i++){
		long x;
		cin >> x;
		all -= x;
	}
	if(!all){
		cout << "YES" << endl;
	}else{
		cout << "NO" << endl;
	}
}