#include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#include<utility>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<functional>
#include<math.h>
#include<random>
#include <bitset>
using namespace std;
//#define N (1000000000+7)
#define N 998244353
#define INF 1e16
typedef long long ll;
typedef pair<int,int> P;
typedef pair<int,P> Q;

const int inf = (int)1e9; 

ll gcd(ll a, ll b) {
	if (b > a) {
		ll tmp = b;
		b = a;
		a = tmp;
	}
	if (a%b == 0)return b;
	else return gcd(b, a%b);
}


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