#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)s; i < (int)e; ++i)
#define all(a) (a).begin(),(a).end()

int main() {
    cin.tie(nullptr);
    
    ll n, a;
    cin >> n >> a;
    
    ll sum = 0;
    rep(i, 0, n) {
        ll input;
        cin >> input;
        sum += input;
    }
    
    if (sum == a * n) cout << "YES\n";
    else cout << "NO\n";
}