#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);

    ll n,a; cin >> n >> a;
    ll s = 0;
    rep(i,n){
        ll x; cin >> x;
        s += x;
    }
    cout << (s == n * a ? "YES" : "NO") << endl;
}