#include <iostream>
using namespace std;

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

    int x;
    double sum = 0;
    for(int i = 0; i < n; i++){
        cin >> x;
        sum += x;
    }

    cout << ((a == sum / n) ? "YES" : "NO") << endl;

    return 0;
}