#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define REP(i, n) for(int i = 0; i < n; i++)

int main() {
    ll n, a;
    cin >> n >> a;
    ll x[n];
    ll dif = n * a;
    REP(i, n) {
        cin >> x[i];
        dif -= x[i];
    }

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

    return 0;
}