#include <bits/stdc++.h>
#define FOR(i,bg,ed) for(ll i=(bg);i<(ed);i++)
#define REP(i,n) FOR(i,0,n)
#define MOD 1000000007
#define int long long
using namespace std;
typedef long long ll;
typedef vector<vector<ll>> mat;
const int INF = 1e9;



signed main()
{
    int n, a;
    int x[10];
    
    cin >> n >> a;
    int sum = 0;
    REP(i,n) {
        cin >> x[i];
        sum += x[i];
    }
    
    if (sum % n != 0) {
        cout << "NO" << endl;
    } else if (sum / n == a) {
        cout << "YES" << endl;
    } else {
        cout << "NO" << endl;
    }
}