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

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

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

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