#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <stack>
#include <algorithm>
#include <string>
#include <map>
#include <iterator>
#include <set>
#include <queue>

using namespace std;


int main() {

    int n;
    long a;
    cin >> n >> a;
    long s = 0;
    for (int i = 0; i < n; ++i) {
        long x;
        cin >> x;
        s += x;
    }

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

    return 0;
}