#include <bits/stdc++.h>
using namespace std;
int main(){
    int n,num;
    double a;
    cin >> n >> a;
    double sum=0;
    for(int i=0; i < n; i++){
        cin >> num;
        sum += num;
    }
    cout << (sum/n == a ? "YES" : "NO") << endl;
}