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**/
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,n) for(int i=0;i<(int)(n);++i)
int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    ll n, a; cin >> n >> a;
    ll res = 0;
    rep(i,n) {
        ll b; cin >> b;
        res += b;
    }
    cout << ((res+0.0)/(n+0.0) == a ? "YES" : "NO") << endl;
}