#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
typedef long long int ll;

int main(){
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	int n; cin >> n;
	ll k; cin >> k;
	vector<ll> a(n);
	ll sum=0;
	for(int i=0;i<n;i++){
		cin >> a[i];
		sum+=a[i];
	}
	if(sum==k*n){
		cout << "YES" << endl;
	}
	else{
		cout << "NO" << endl;
	}
}