#include<iostream>
#include<string>
#include<cstring>
#include<complex>
#include<vector>
#include<algorithm>
using namespace std;

#define REP(i, j) for (int i = 0; i < (int)j; ++i)
#define FOR(i, j, k) for (int i = (int)j; i < (int)k; ++i)
#define SORT(v) sort(v.begin(), v.end())
#define REVERSE(v) reverse(v.begin(), v.end())
typedef complex<double> P;
typedef vector<int> VI;
typedef long long LL;
typedef pair<int,int> PII;

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

	int n;
	LL sum = 0;
	double a, avg;
	cin >> n >> a;
	REP(i,n) {
		int x;
		cin >> x;
		sum += x;
	}
	avg = (double)sum / n;

	cout << (a == avg ? "YES" : "NO") << endl;

	return 0;
}