#include <bits/stdc++.h>

using namespace std;

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