#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<vector>
#include<string.h>
#include<math.h>
#include<map>
#include<iomanip>
#include<queue>

const long long INF = 1e6+7;
const long long MOD = 1e9+7;
const double PI=acos(-1);

using namespace std;

int main(){
	long long n,a;
	cin >> n >> a;
	long long sum=0;
	for(long long i=0;i<n;i++){
		int temp;
		cin >> temp;
		sum+=temp;
	}
	double ave=(double)sum/(double)n;
	if(ave==a){
		cout << "YES" << endl;
	}else{
		cout << "NO" << endl;
	}
	return 0;
}