#include<iostream>
using namespace std;

long long n, a, x, sum = 0;

int main(){

	cin >> n >> a;

	for (int i = 0; i < n; i++){
		cin >> x;
		
		sum += x;
	}

	if (sum == a * n){
		cout << "YES";
	}
	else{
		cout << "NO";
	}

	cout << "\n";

	return 0;
}