#include "iostream"
#include "climits"
#include "list"
#include "queue"
#include "set"
#include "functional"
#include "algorithm"
#include "math.h"
#include "utility"

using namespace std;
const long long int MOD = 1000000007;


long long int N,K;
long long int num;
long long int sum;

int main() {
	cin >> N>>K;
	for (int i = 0; i < N; i++) {
		cin >> num;
		sum += num;
	}
	if (K*N == sum) {
		cout << "YES\n";
	}
	else cout << "NO\n";
	return 0;
}