#include <iostream>
#include <cmath>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
typedef long long lint;

#define MIN(a,b) ((a)<(b)?(a):(b))
#define MAX(a,b) ((a)>(b)?(a):(b))



int main()
{
	lint n, a, sum = 0, t;
	cin >> n >> a;
	for (lint i = 0; i < n; i++)
		cin >> t, sum += t;
	cout << (a * n == sum ? "YES" : "NO") << endl;
	return 0;
}