#include <bits/stdc++.h>
using namespace std;

int main(){
    int n; double a; cin >> n >> a;
    double mean = 0;
    for(int i = 0; i < n; ++i){
        double x; cin >> x;
        mean += x;
    }
    cout << (mean / n == a ? "YES" : "NO") << endl;
}