#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <string.h>
#include <vector>
using namespace std;

#define ll long long
#define INF (1 << 30)
#define INFLL (1LL << 60)

#define FOR(i,a,b) for(ll i = (a);i<(b);i++)
#define REP(i,a) FOR(i,0,(a))
#define MP make_pair

int main() {
	ll n, a, sum = 0, x;
	cin >> n >> a;
	for(int i = 0;i < n;i++){
		cin >> x;
		sum += x;
	}
	if(sum % n == 0 && sum / n == a){
		cout << "YES" << endl;
	}else{
		cout << "NO" << endl;
	}
	return 0;
}