#include<iostream>

using namespace std;

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