#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <utility>
#include <iomanip>
using namespace std;

int main(void) {
	long long int n, a, x, ans = 0;
	cin >> n >> a;
	for (int i = 0; i < n; i++) {
		cin >> x;
		ans += x;
	}
	if (ans / n == a && ans % n == 0)	cout << "YES" << endl;
	else								cout << "NO" << endl;
	return 0;
}