#include <bits/stdc++.h>
using namespace std;

int main() {
	int64_t n, a;
	cin >> n >> a;

	int64_t s = 0;
	for (int i = 0; i < n; i++) {
		int n;
		cin >> n;
		s += n;
	}

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