#include <bits/stdc++.h>

using namespace std;

int main() {
    long long n, a;
    cin >> n >> a;

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

    if (dif == 0) {
        cout << "YES" << endl;
    } else {
        cout << "NO" << endl;
    }
    return 0;
}