#include <iostream>

int main() {
    using namespace std;
    long long n, a, tot = 0;
    cin >> n >> a;
    for (int _ = 0; _ < n; _++) {
        long long x;
        cin >> x;
        tot += x;
    }
    cout << (a * n == tot ? "YES\n" : "NO\n");
}