#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
#include<stdio.h>
#include<cmath>
#include<vector>
#include<utility>
#define FOR(i, a, b) for(int i=(a);i<=(b);i++)
#define RFOR(i, a, b) for(int i=(a);i>=(b);i--)
#define MOD 1000000007

using namespace std;


int main(void) {
	int n;
	double a;
	double x[11];
	double p = 0;
	cin >> n >> a;
	FOR(i, 1, n) {
		cin >> x[i];
		p += x[i];
	}
	p /= n;
	if (p == a) {
		cout << "YES" << endl;
	}
	else {
		cout << "NO" << endl;
	}
	return 0;
}