#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define pb push_back
#define mp make_pair
#define rep(i,n) for(int i=0;i<(n);++i)

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	ll n,a;cin >> n >> a;
	ll sum=0;
	rep(i,n){
		int x;cin >> x;
		sum+=x;
	}
	if(sum%n==0 && sum/n==a) cout << "YES" << endl;
	else cout << "NO" << endl;
}