#include <iostream>
#include <vector>
using namespace std;
using ll = long long;

int main() {
    ll n, a;
    cin >> n >> a;
    ll sum = 0;
    for(int i=0; i<n; ++i) {
        ll x; cin >> x;
        sum += x;
    }
    if(sum % n != 0 || sum / n != a) {
        cout << "NO" << endl;
    } else {
        cout << "YES" << endl;
    }
}