#include <iostream>
#include <stdio.h>
#include <algorithm>
#include <vector>
#include <cmath>
#include <string>
#include <sstream>
#include<sstream>
#include <queue>
#include <limits>
#include <cstdlib>
#include <deque>
#include <map>
#include <set>
using namespace std;

int main() {

	int n =0;
	long a =0;

	cin>>n>>a;

	long sum =0;

	long tmp=0;

	for(int i=0; i<n; i++){
		cin>>tmp;

		sum +=tmp;
	}
	if(sum == n*a){
		cout<<"YES"<<endl;
	}else {
		cout<<"NO"<<endl;
	}

	return 0;
}