#include <iostream>
#include <string>
using namespace std;
#define REP(i, N) for(int i=0;i<(N);++i)

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

    long long sum = 0;
    REP(i, n) {
        int x; cin >> x;
        sum += x;
    }

    if (sum % n != 0) {
        cout << "NO" << endl;
    } else if (sum / n == a) {
        cout << "YES" << endl;
    } else {
        cout << "NO" << endl;
    }
}